diff --git a/dom/base/DocumentOrShadowRoot.cpp b/dom/base/DocumentOrShadowRoot.cpp
index 44551b4dfdc7..fe93b1a61e27 100644
--- a/dom/base/DocumentOrShadowRoot.cpp
+++ b/dom/base/DocumentOrShadowRoot.cpp
@@ -10,7 +10,6 @@
 #include "mozilla/PointerLockManager.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/StyleSheet.h"
-#include "mozilla/SVGUtils.h"
 #include "mozilla/dom/AnimatableBinding.h"
 #include "mozilla/dom/Document.h"
 #include "mozilla/dom/HTMLInputElement.h"
@@ -414,7 +413,7 @@ static void QueryNodesFromRect(DocumentOrShadowRoot& aRoot, const nsRect& aRect,
       // SVG 'text' element's SVGTextFrame doesn't respond to hit-testing, so
       // if 'content' is a child of such an element then we need to manually
       // defer to the parent here.
-      if (aMultiple == Multiple::Yes && !SVGUtils::IsInSVGTextSubtree(frame)) {
+      if (aMultiple == Multiple::Yes && !frame->IsInSVGTextSubtree()) {
         continue;
       }
 
diff --git a/dom/svg/SVGGraphicsElement.cpp b/dom/svg/SVGGraphicsElement.cpp
index c1b4620d95e4..91ee7cdea059 100644
--- a/dom/svg/SVGGraphicsElement.cpp
+++ b/dom/svg/SVGGraphicsElement.cpp
@@ -61,7 +61,7 @@ already_AddRefed<SVGRect> SVGGraphicsElement::GetBBox(
   ISVGDisplayableFrame* svgframe = do_QueryFrame(frame);
 
   if (!svgframe) {
-    if (!SVGUtils::IsInSVGTextSubtree(frame)) {
+    if (!frame->IsInSVGTextSubtree()) {
       return ZeroBBox(*this);
     }
 
diff --git a/layout/base/RestyleManager.cpp b/layout/base/RestyleManager.cpp
index c323f53506fe..42adbc621261 100644
--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -991,7 +991,7 @@ static bool ContainingBlockChangeAffectsDescendants(
         nsIFrame* outOfFlow = nsPlaceholderFrame::GetRealFrameForPlaceholder(f);
         // If SVG text frames could appear here, they could confuse us since
         // they ignore their position style ... but they can't.
-        NS_ASSERTION(!SVGUtils::IsInSVGTextSubtree(outOfFlow),
+        NS_ASSERTION(!outOfFlow->IsInSVGTextSubtree(),
                      "SVG text frames can't be out of flow");
         // Top-layer frames don't change containing block based on direct
         // ancestors.
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 839e65fdaab9..dd9b4b165b06 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -119,7 +119,6 @@
 #include "mozilla/dom/SVGFilters.h"
 #include "mozilla/dom/SVGTests.h"
 #include "mozilla/SVGGradientFrame.h"
-#include "mozilla/SVGUtils.h"
 
 #include "nsRefreshDriver.h"
 #include "nsTextNode.h"
@@ -286,8 +285,7 @@ static inline bool IsDisplayContents(const nsIContent* aContent) {
  * frame being used for SVG text.
  */
 static bool IsFrameForSVG(const nsIFrame* aFrame) {
-  return aFrame->IsFrameOfType(nsIFrame::eSVG) ||
-         SVGUtils::IsInSVGTextSubtree(aFrame);
+  return aFrame->IsFrameOfType(nsIFrame::eSVG) || aFrame->IsInSVGTextSubtree();
 }
 
 static bool IsLastContinuationForColumnContent(const nsIFrame* aFrame) {
@@ -935,8 +933,7 @@ nsContainerFrame* nsFrameConstructorState::GetGeometricParent(
   // XXXbz couldn't we just force position to "static" on roots and
   // float to "none"?  That's OK per CSS 2.1, as far as I can tell.
 
-  if (aContentParentFrame &&
-      SVGUtils::IsInSVGTextSubtree(aContentParentFrame)) {
+  if (aContentParentFrame && aContentParentFrame->IsInSVGTextSubtree()) {
     return aContentParentFrame;
   }
 
@@ -3338,7 +3335,7 @@ const nsCSSFrameConstructor::FrameConstructionData*
 nsCSSFrameConstructor::FindTextData(const Text& aTextContent,
                                     nsIFrame* aParentFrame) {
   if (aParentFrame && IsFrameForSVG(aParentFrame)) {
-    if (!SVGUtils::IsInSVGTextSubtree(aParentFrame)) {
+    if (!aParentFrame->IsInSVGTextSubtree()) {
       return nullptr;
     }
 
@@ -4578,7 +4575,7 @@ nsIFrame* nsCSSFrameConstructor::ConstructNonScrollableBlock(
   if ((aDisplay->IsAbsolutelyPositionedStyle() || aDisplay->IsFloatingStyle() ||
        aDisplay->DisplayInside() == StyleDisplayInside::FlowRoot ||
        clipPaginatedOverflow) &&
-      !SVGUtils::IsInSVGTextSubtree(aParentFrame)) {
+      !aParentFrame->IsInSVGTextSubtree()) {
     flags = NS_BLOCK_FORMATTING_CONTEXT_STATE_BITS;
     if (clipPaginatedOverflow) {
       flags |= NS_BLOCK_CLIP_PAGINATED_OVERFLOW;
@@ -5151,7 +5148,7 @@ void nsCSSFrameConstructor::AddFrameConstructionItems(
   RefPtr<ComputedStyle> computedStyle = ResolveComputedStyle(aContent);
   auto flags = aFlags + ItemFlag::AllowPageBreak;
   if (parentFrame) {
-    if (SVGUtils::IsInSVGTextSubtree(parentFrame)) {
+    if (parentFrame->IsInSVGTextSubtree()) {
       flags += ItemFlag::IsWithinSVGText;
     }
     if (parentFrame->IsBlockFrame() && parentFrame->GetParent() &&
@@ -10134,8 +10131,7 @@ void nsCSSFrameConstructor::CreateLetterFrame(
     // Create the right type of first-letter frame
     const nsStyleDisplay* display = sc->StyleDisplay();
     nsFirstLetterFrame* letterFrame;
-    if (display->IsFloatingStyle() &&
-        !SVGUtils::IsInSVGTextSubtree(aParentFrame)) {
+    if (display->IsFloatingStyle() && !aParentFrame->IsInSVGTextSubtree()) {
       // Make a floating first-letter frame
       letterFrame = CreateFloatingLetterFrame(state, aTextContent, textFrame,
                                               aParentFrame, parentComputedStyle,
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index b7690007cba4..b9313dd45cd9 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -1714,7 +1714,7 @@ nsPoint GetEventCoordinatesRelativeTo(nsIWidget* aWidget,
   /* If we encountered a transform, we can't do simple arithmetic to figure
    * out how to convert back to aFrame's coordinates and must use the CTM.
    */
-  if (transformFound || SVGUtils::IsInSVGTextSubtree(frame)) {
+  if (transformFound || frame->IsInSVGTextSubtree()) {
     return nsLayoutUtils::TransformRootPointToFrame(ViewportType::Visual,
                                                     aFrame, widgetToView);
   }
@@ -2254,7 +2254,7 @@ bool nsLayoutUtils::AuthorSpecifiedBorderBackgroundDisablesTheming(
 }
 
 static SVGTextFrame* GetContainingSVGTextFrame(const nsIFrame* aFrame) {
-  if (!SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (!aFrame->IsInSVGTextSubtree()) {
     return nullptr;
   }
 
@@ -8050,7 +8050,7 @@ nscoord nsLayoutUtils::InflationMinFontSizeFor(const nsIFrame* aFrame) {
 }
 
 float nsLayoutUtils::FontSizeInflationFor(const nsIFrame* aFrame) {
-  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (aFrame->IsInSVGTextSubtree()) {
     const nsIFrame* container = aFrame;
     while (!container->IsSVGTextFrame()) {
       container = container->GetParent();
diff --git a/layout/generic/ReflowInput.cpp b/layout/generic/ReflowInput.cpp
index 300597ed3845..3325c14f60aa 100644
--- a/layout/generic/ReflowInput.cpp
+++ b/layout/generic/ReflowInput.cpp
@@ -14,7 +14,6 @@
 #include "LayoutLogging.h"
 #include "mozilla/dom/HTMLInputElement.h"
 #include "mozilla/StaticPrefs_layout.h"
-#include "mozilla/SVGUtils.h"
 #include "mozilla/WritingModes.h"
 #include "nsBlockFrame.h"
 #include "nsCSSAnonBoxes.h"
@@ -2494,7 +2493,7 @@ void SizeComputationInput::InitOffsets(WritingMode aCBWM, nscoord aPercentBasis,
         widgetPadding, presContext->AppUnitsPerDevPixel());
     SetComputedLogicalPadding(wm, LogicalMargin(wm, padding));
     needPaddingProp = false;
-  } else if (SVGUtils::IsInSVGTextSubtree(mFrame)) {
+  } else if (mFrame->IsInSVGTextSubtree()) {
     SetComputedLogicalPadding(wm, LogicalMargin(wm));
     needPaddingProp = false;
   } else if (aPadding) {  // padding is an input arg
@@ -2548,7 +2547,7 @@ void SizeComputationInput::InitOffsets(WritingMode aCBWM, nscoord aPercentBasis,
     border = LogicalMargin(
         wm, LayoutDevicePixel::ToAppUnits(widgetBorder,
                                           presContext->AppUnitsPerDevPixel()));
-  } else if (SVGUtils::IsInSVGTextSubtree(mFrame)) {
+  } else if (mFrame->IsInSVGTextSubtree()) {
     // Do nothing since the border local variable is initialized all zero.
   } else if (aBorder) {  // border is an input arg
     border = *aBorder;
@@ -2835,7 +2834,7 @@ bool SizeComputationInput::ComputeMargin(WritingMode aCBWM,
                                          nscoord aPercentBasis,
                                          LayoutFrameType aFrameType) {
   // SVG text frames have no margin.
-  if (SVGUtils::IsInSVGTextSubtree(mFrame)) {
+  if (mFrame->IsInSVGTextSubtree()) {
     return false;
   }
 
diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index 3006ea6307fd..61c265708edc 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -21,7 +21,6 @@
 #include "mozilla/PresShell.h"
 #include "mozilla/StaticPrefs_browser.h"
 #include "mozilla/StaticPrefs_layout.h"
-#include "mozilla/SVGUtils.h"
 #include "mozilla/ToString.h"
 #include "mozilla/UniquePtr.h"
 
@@ -577,7 +576,7 @@ nsresult nsBlockFrame::GetFrameName(nsAString& aResult) const {
 
 void nsBlockFrame::InvalidateFrame(uint32_t aDisplayItemKey,
                                    bool aRebuildDisplayItems) {
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     NS_ASSERTION(GetParent()->IsSVGTextFrame(),
                  "unexpected block frame in SVG text");
     GetParent()->InvalidateFrame();
@@ -589,7 +588,7 @@ void nsBlockFrame::InvalidateFrame(uint32_t aDisplayItemKey,
 void nsBlockFrame::InvalidateFrameWithRect(const nsRect& aRect,
                                            uint32_t aDisplayItemKey,
                                            bool aRebuildDisplayItems) {
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     NS_ASSERTION(GetParent()->IsSVGTextFrame(),
                  "unexpected block frame in SVG text");
     GetParent()->InvalidateFrame();
@@ -2359,8 +2358,7 @@ static inline bool IsAlignedLeft(StyleTextAlign aAlignment,
                                  StyleDirection aDirection,
                                  StyleUnicodeBidi aUnicodeBidi,
                                  nsIFrame* aFrame) {
-  return SVGUtils::IsInSVGTextSubtree(aFrame) ||
-         StyleTextAlign::Left == aAlignment ||
+  return aFrame->IsInSVGTextSubtree() || StyleTextAlign::Left == aAlignment ||
          (((StyleTextAlign::Start == aAlignment &&
             StyleDirection::Ltr == aDirection) ||
            (StyleTextAlign::End == aAlignment &&
@@ -5172,7 +5170,7 @@ bool nsBlockFrame::PlaceLine(BlockReflowState& aState,
    * In other words, isLastLine really means isLastLineAndWeCare.
    */
   const bool isLastLine =
-      !SVGUtils::IsInSVGTextSubtree(this) &&
+      !IsInSVGTextSubtree() &&
       styleText->TextAlignForLastLine() != styleText->mTextAlign &&
       (aLineLayout.GetLineEndsInBR() || IsLastLine(aState, aLine));
 
@@ -5764,7 +5762,7 @@ void nsBlockFrame::AppendFrames(ChildListID aListID, nsFrameList&& aFrameList) {
   printf("\n");
 #endif
 
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     MOZ_ASSERT(GetParent()->IsSVGTextFrame(),
                "unexpected block frame in SVG text");
     // Workaround for bug 1399425 in case this bit has been removed from the
diff --git a/layout/generic/nsIFrame.cpp b/layout/generic/nsIFrame.cpp
index 91350f162ad4..e74eebc1f506 100644
--- a/layout/generic/nsIFrame.cpp
+++ b/layout/generic/nsIFrame.cpp
@@ -543,7 +543,7 @@ static bool IsFontSizeInflationContainer(nsIFrame* aFrame,
 }
 
 static void MaybeScheduleReflowSVGNonDisplayText(nsIFrame* aFrame) {
-  if (!SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (!aFrame->IsInSVGTextSubtree()) {
     return;
   }
 
@@ -1570,7 +1570,7 @@ void nsIFrame::CreateView() {
 nsMargin nsIFrame::GetUsedMargin() const {
   nsMargin margin(0, 0, 0, 0);
   if (((mState & NS_FRAME_FIRST_REFLOW) && !(mState & NS_FRAME_IN_REFLOW)) ||
-      SVGUtils::IsInSVGTextSubtree(this))
+      IsInSVGTextSubtree())
     return margin;
 
   nsMargin* m = GetProperty(UsedMarginProperty());
@@ -1591,7 +1591,7 @@ nsMargin nsIFrame::GetUsedMargin() const {
 nsMargin nsIFrame::GetUsedBorder() const {
   nsMargin border(0, 0, 0, 0);
   if (((mState & NS_FRAME_FIRST_REFLOW) && !(mState & NS_FRAME_IN_REFLOW)) ||
-      SVGUtils::IsInSVGTextSubtree(this))
+      IsInSVGTextSubtree())
     return border;
 
   // Theme methods don't use const-ness.
@@ -1620,7 +1620,7 @@ nsMargin nsIFrame::GetUsedBorder() const {
 nsMargin nsIFrame::GetUsedPadding() const {
   nsMargin padding(0, 0, 0, 0);
   if (((mState & NS_FRAME_FIRST_REFLOW) && !(mState & NS_FRAME_IN_REFLOW)) ||
-      SVGUtils::IsInSVGTextSubtree(this))
+      IsInSVGTextSubtree())
     return padding;
 
   // Theme methods don't use const-ness.
@@ -5637,7 +5637,7 @@ static FrameTarget GetSelectionClosestFrame(nsIFrame* aFrame,
       kid->FindCloserFrameForSelection(aPoint, &closest);
     }
     if (closest.mFrame) {
-      if (SVGUtils::IsInSVGTextSubtree(closest.mFrame))
+      if (closest.mFrame->IsInSVGTextSubtree())
         return FrameTarget{closest.mFrame, false, false};
       return GetSelectionClosestFrameForChild(closest.mFrame, aPoint, aFlags);
     }
@@ -5754,7 +5754,7 @@ nsIFrame::ContentOffsets nsIFrame::GetContentOffsetsFromPoint(
 
   nsPoint pt;
   if (closest.frame != this) {
-    if (SVGUtils::IsInSVGTextSubtree(closest.frame)) {
+    if (closest.frame->IsInSVGTextSubtree()) {
       pt = nsLayoutUtils::TransformAncestorPointToFrame(
           RelativeTo{closest.frame}, aPoint, RelativeTo{this});
     } else {
@@ -10622,7 +10622,7 @@ static StyleVerticalAlignKeyword ConvertSVGDominantBaselineToVerticalAlign(
 }
 
 Maybe<StyleVerticalAlignKeyword> nsIFrame::VerticalAlignEnum() const {
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     StyleDominantBaseline dominantBaseline = StyleSVG()->mDominantBaseline;
     return Some(ConvertSVGDominantBaselineToVerticalAlign(dominantBaseline));
   }
diff --git a/layout/generic/nsIFrame.h b/layout/generic/nsIFrame.h
index bb86580154c1..318c37e3f456 100644
--- a/layout/generic/nsIFrame.h
+++ b/layout/generic/nsIFrame.h
@@ -4513,6 +4513,13 @@ class nsIFrame : public nsQueryFrame {
     return HasAnyStateBits(NS_FRAME_IS_DIRTY | NS_FRAME_HAS_DIRTY_CHILDREN);
   }
 
+  /**
+   * Returns true if the frame is an SVGTextFrame or one of its descendants.
+   */
+  bool IsInSVGTextSubtree() const {
+    return HasAnyStateBits(NS_FRAME_IS_SVG_TEXT);
+  }
+
   /**
    * Return whether this frame keeps track of overflow areas. (Frames for
    * non-display SVG elements -- e.g. <clipPath> -- do not maintain overflow
diff --git a/layout/generic/nsInlineFrame.cpp b/layout/generic/nsInlineFrame.cpp
index 4c03d8fca031..ec5ea2068fab 100644
--- a/layout/generic/nsInlineFrame.cpp
+++ b/layout/generic/nsInlineFrame.cpp
@@ -15,7 +15,6 @@
 #include "mozilla/RestyleManager.h"
 #include "mozilla/ServoStyleSet.h"
 #include "mozilla/SVGTextFrame.h"
-#include "mozilla/SVGUtils.h"
 #include "nsLineLayout.h"
 #include "nsBlockFrame.h"
 #include "nsLayoutUtils.h"
@@ -56,7 +55,7 @@ nsresult nsInlineFrame::GetFrameName(nsAString& aResult) const {
 
 void nsInlineFrame::InvalidateFrame(uint32_t aDisplayItemKey,
                                     bool aRebuildDisplayItems) {
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     nsIFrame* svgTextFrame = nsLayoutUtils::GetClosestFrameOfType(
         GetParent(), LayoutFrameType::SVGText);
     svgTextFrame->InvalidateFrame();
@@ -68,7 +67,7 @@ void nsInlineFrame::InvalidateFrame(uint32_t aDisplayItemKey,
 void nsInlineFrame::InvalidateFrameWithRect(const nsRect& aRect,
                                             uint32_t aDisplayItemKey,
                                             bool aRebuildDisplayItems) {
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     nsIFrame* svgTextFrame = nsLayoutUtils::GetClosestFrameOfType(
         GetParent(), LayoutFrameType::SVGText);
     svgTextFrame->InvalidateFrame();
@@ -373,7 +372,7 @@ nsresult nsInlineFrame::AttributeChanged(int32_t aNameSpaceID,
     return rv;
   }
 
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     SVGTextFrame* f = static_cast<SVGTextFrame*>(
         nsLayoutUtils::GetClosestFrameOfType(this, LayoutFrameType::SVGText));
     f->HandleAttributeChangeInDescendant(mContent->AsElement(), aNameSpaceID,
diff --git a/layout/generic/nsLineLayout.cpp b/layout/generic/nsLineLayout.cpp
index f67d03e2e4f0..84e512267c5c 100644
--- a/layout/generic/nsLineLayout.cpp
+++ b/layout/generic/nsLineLayout.cpp
@@ -10,7 +10,6 @@
 
 #include "mozilla/ComputedStyle.h"
 #include "mozilla/SVGTextFrame.h"
-#include "mozilla/SVGUtils.h"
 
 #include "LayoutLogging.h"
 #include "nsBlockFrame.h"
@@ -79,7 +78,7 @@ nsLineLayout::nsLineLayout(nsPresContext* aPresContext,
       mDirtyNextLine(false),
       mLineAtStart(false),
       mHasRuby(false),
-      mSuppressLineWrap(SVGUtils::IsInSVGTextSubtree(LineContainerFrame()))
+      mSuppressLineWrap(LineContainerFrame()->IsInSVGTextSubtree())
 #ifdef DEBUG
       ,
       mSpansAllocated(0),
@@ -1702,7 +1701,7 @@ void nsLineLayout::AdjustLeadings(nsIFrame* spanFrame, PerSpanData* psd,
 
 static float GetInflationForBlockDirAlignment(nsIFrame* aFrame,
                                               nscoord aInflationMinFontSize) {
-  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (aFrame->IsInSVGTextSubtree()) {
     const nsIFrame* container =
         nsLayoutUtils::GetClosestFrameOfType(aFrame, LayoutFrameType::SVGText);
     NS_ASSERTION(container, "expected to find an ancestor SVGTextFrame");
@@ -3050,7 +3049,7 @@ void nsLineLayout::TextAlignLine(nsLineBox* aLine, bool aIsLastLine) {
   StyleTextAlign textAlign =
       aIsLastLine ? mStyleText->TextAlignForLastLine() : mStyleText->mTextAlign;
 
-  bool isSVG = SVGUtils::IsInSVGTextSubtree(LineContainerFrame());
+  bool isSVG = LineContainerFrame()->IsInSVGTextSubtree();
   bool doTextAlign = remainingISize > 0;
 
   int32_t additionalGaps = 0;
diff --git a/layout/generic/nsTextFrame.cpp b/layout/generic/nsTextFrame.cpp
index 1100e66fe0b6..34da4d9ced98 100644
--- a/layout/generic/nsTextFrame.cpp
+++ b/layout/generic/nsTextFrame.cpp
@@ -21,7 +21,6 @@
 #include "mozilla/StaticPrefs_layout.h"
 #include "mozilla/StaticPresData.h"
 #include "mozilla/SVGTextFrame.h"
-#include "mozilla/SVGUtils.h"
 #include "mozilla/TextEditor.h"
 #include "mozilla/TextEvents.h"
 #include "mozilla/BinarySearch.h"
@@ -608,8 +607,7 @@ static void InvalidateFrameDueToGlyphsChanged(nsIFrame* aFrame) {
     // to reflow the SVGTextFrame. (This is similar to reflowing the
     // SVGTextFrame in response to style changes, in
     // SVGTextFrame::DidSetComputedStyle.)
-    if (SVGUtils::IsInSVGTextSubtree(f) &&
-        f->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY)) {
+    if (f->IsInSVGTextSubtree() && f->HasAnyStateBits(NS_FRAME_IS_NONDISPLAY)) {
       auto* svgTextFrame = static_cast<SVGTextFrame*>(
           nsLayoutUtils::GetClosestFrameOfType(f, LayoutFrameType::SVGText));
       svgTextFrame->ScheduleReflowSVGNonDisplayText(IntrinsicDirty::None);
@@ -1405,7 +1403,7 @@ static void BuildTextRuns(DrawTarget* aDrawTarget, nsTextFrame* aForFrame,
   }
 
   nsPresContext* presContext = aLineContainer->PresContext();
-  bool doLineBreaking = !SVGUtils::IsInSVGTextSubtree(aForFrame);
+  bool doLineBreaking = !aForFrame->IsInSVGTextSubtree();
   BuildTextRunsScanner scanner(presContext, aDrawTarget, aLineContainer,
                                aWhichTextRun, doLineBreaking);
 
@@ -1748,7 +1746,7 @@ static gfxFloat GetMinTabAdvanceAppUnits(const gfxTextRun* aTextRun) {
 }
 
 static float GetSVGFontSizeScaleFactor(nsIFrame* aFrame) {
-  if (!SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (!aFrame->IsInSVGTextSubtree()) {
     return 1.0f;
   }
   auto* container =
@@ -1758,7 +1756,7 @@ static float GetSVGFontSizeScaleFactor(nsIFrame* aFrame) {
 }
 
 static nscoord LetterSpacing(nsIFrame* aFrame, const nsStyleText& aStyleText) {
-  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (aFrame->IsInSVGTextSubtree()) {
     // SVG text can have a scaling factor applied so that very small or very
     // large font-sizes don't suffer from poor glyph placement due to app unit
     // rounding. The used letter-spacing value must be scaled by the same
@@ -1774,7 +1772,7 @@ static nscoord LetterSpacing(nsIFrame* aFrame, const nsStyleText& aStyleText) {
 // This function converts non-coord values (e.g. percentages) to nscoord.
 static nscoord WordSpacing(nsIFrame* aFrame, const gfxTextRun* aTextRun,
                            const nsStyleText& aStyleText) {
-  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (aFrame->IsInSVGTextSubtree()) {
     // SVG text can have a scaling factor applied so that very small or very
     // large font-sizes don't suffer from poor glyph placement due to app unit
     // rounding. The used word-spacing value must be scaled by the same
@@ -1913,7 +1911,7 @@ bool BuildTextRunsScanner::ContinueTextRunAcrossFrames(nsTextFrame* aFrame1,
     // as there are too many things SVG might be doing (like applying per-
     // element positioning) that wouldn't make sense with shaping across
     // the boundary.
-    if (SVGUtils::IsInSVGTextSubtree(ancestor)) {
+    if (ancestor->IsInSVGTextSubtree()) {
       return false;
     }
 
@@ -2200,7 +2198,7 @@ already_AddRefed<gfxTextRun> BuildTextRunsScanner::BuildTextRunForFrames(
 
   uint32_t nextBreakIndex = 0;
   nsTextFrame* nextBreakBeforeFrame = GetNextBreakBeforeFrame(&nextBreakIndex);
-  bool isSVG = SVGUtils::IsInSVGTextSubtree(mLineContainer);
+  bool isSVG = mLineContainer->IsInSVGTextSubtree();
   bool enabledJustification =
       (mLineContainer->StyleText()->mTextAlign == StyleTextAlign::Justify ||
        mLineContainer->StyleText()->mTextAlignLast ==
@@ -4235,7 +4233,7 @@ void nsTextFrame::InvalidateFrame(uint32_t aDisplayItemKey,
                                   bool aRebuildDisplayItems) {
   InvalidateSelectionState();
 
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     nsIFrame* svgTextFrame = nsLayoutUtils::GetClosestFrameOfType(
         GetParent(), LayoutFrameType::SVGText);
     svgTextFrame->InvalidateFrame();
@@ -4249,7 +4247,7 @@ void nsTextFrame::InvalidateFrameWithRect(const nsRect& aRect,
                                           bool aRebuildDisplayItems) {
   InvalidateSelectionState();
 
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     nsIFrame* svgTextFrame = nsLayoutUtils::GetClosestFrameOfType(
         GetParent(), LayoutFrameType::SVGText);
     svgTextFrame->InvalidateFrame();
@@ -4488,7 +4486,7 @@ void nsTextFrame::BuildDisplayList(nsDisplayListBuilder* aBuilder,
       NS_GET_A(st->mWebkitTextStrokeColor.CalcColor(this)) == 0;
   if ((HasAnyStateBits(TEXT_NO_RENDERED_GLYPHS) ||
        (isTextTransparent && !StyleText()->HasTextShadow())) &&
-      aBuilder->IsForPainting() && !SVGUtils::IsInSVGTextSubtree(this)) {
+      aBuilder->IsForPainting() && !IsInSVGTextSubtree()) {
     if (!IsSelected()) {
       TextDecorations textDecs;
       GetTextDecorations(PresContext(), eResolvedColors, textDecs);
@@ -4680,7 +4678,7 @@ void nsTextFrame::GetTextDecorations(
       nscolor color;
       if (useOverride) {
         color = overrideColor;
-      } else if (SVGUtils::IsInSVGTextSubtree(this)) {
+      } else if (IsInSVGTextSubtree()) {
         // XXX We might want to do something with text-decoration-color when
         //     painting SVG text, but it's not clear what we should do.  We
         //     at least need SVG text decorations to paint with 'fill' if
@@ -4760,7 +4758,7 @@ void nsTextFrame::GetTextDecorations(
 
 static float GetInflationForTextDecorations(nsIFrame* aFrame,
                                             nscoord aInflationMinFontSize) {
-  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (aFrame->IsInSVGTextSubtree()) {
     auto* container =
         nsLayoutUtils::GetClosestFrameOfType(aFrame, LayoutFrameType::SVGText);
     MOZ_ASSERT(container);
@@ -6192,7 +6190,7 @@ nscolor nsTextFrame::GetCaretColorAt(int32_t aOffset) {
   }
 
   bool isSolidTextColor = true;
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     const nsStyleSVG* style = StyleSVG();
     if (!style->mFill.kind.IsNone() && !style->mFill.kind.IsColor()) {
       isSolidTextColor = false;
@@ -6383,7 +6381,7 @@ void nsTextFrame::PaintText(const PaintTextParams& aParams,
                             const bool aIsSelected,
                             float aOpacity /* = 1.0f */) {
 #ifdef DEBUG
-  if (SVGUtils::IsInSVGTextSubtree(this)) {
+  if (IsInSVGTextSubtree()) {
     auto* container =
         nsLayoutUtils::GetClosestFrameOfType(this, LayoutFrameType::SVGText);
     MOZ_ASSERT(container);
@@ -9473,7 +9471,7 @@ void nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
        lineContainer->StyleText()->mTextAlignLast ==
            StyleTextAlignLast::Justify ||
        shouldSuppressLineBreak) &&
-      !SVGUtils::IsInSVGTextSubtree(lineContainer)) {
+      !lineContainer->IsInSVGTextSubtree()) {
     AddStateBits(TEXT_JUSTIFICATION_ENABLED);
     Range range(uint32_t(offset), uint32_t(offset + charsFit));
     aLineLayout.SetJustificationInfo(provider.ComputeJustification(range));
diff --git a/layout/generic/nsTextPaintStyle.cpp b/layout/generic/nsTextPaintStyle.cpp
index cf34225ad976..61934e1bfe20 100644
--- a/layout/generic/nsTextPaintStyle.cpp
+++ b/layout/generic/nsTextPaintStyle.cpp
@@ -88,7 +88,7 @@ bool nsTextPaintStyle::EnsureSufficientContrast(nscolor* aForeColor,
 }
 
 nscolor nsTextPaintStyle::GetTextColor() {
-  if (SVGUtils::IsInSVGTextSubtree(mFrame)) {
+  if (mFrame->IsInSVGTextSubtree()) {
     if (!mResolveColors) {
       return NS_SAME_AS_FOREGROUND_COLOR;
     }
@@ -559,14 +559,14 @@ nscolor nsTextPaintStyle::GetResolvedForeColor(nscolor aColor,
 }
 
 nscolor nsTextPaintStyle::GetWebkitTextStrokeColor() {
-  if (mozilla::SVGUtils::IsInSVGTextSubtree(mFrame)) {
+  if (mFrame->IsInSVGTextSubtree()) {
     return 0;
   }
   return mFrame->StyleText()->mWebkitTextStrokeColor.CalcColor(mFrame);
 }
 
 float nsTextPaintStyle::GetWebkitTextStrokeWidth() {
-  if (mozilla::SVGUtils::IsInSVGTextSubtree(mFrame)) {
+  if (mFrame->IsInSVGTextSubtree()) {
     return 0.0f;
   }
   nscoord coord = mFrame->StyleText()->mWebkitTextStrokeWidth;
diff --git a/layout/style/ComputedStyleInlines.h b/layout/style/ComputedStyleInlines.h
index e208ce033c55..5fa74c747109 100644
--- a/layout/style/ComputedStyleInlines.h
+++ b/layout/style/ComputedStyleInlines.h
@@ -88,7 +88,7 @@ bool ComputedStyle::IsFixedPosContainingBlock(
     const nsIFrame* aContextFrame) const {
   // NOTE: Any CSS properties that influence the output of this function
   // should also handle will-change appropriately.
-  if (mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame)) {
+  if (aContextFrame->IsInSVGTextSubtree()) {
     return false;
   }
   if (IsFixedPosContainingBlockForNonSVGTextFrames()) {
@@ -114,7 +114,7 @@ bool ComputedStyle::IsAbsPosContainingBlock(
   // NOTE: Any CSS properties that influence the output of this function
   // should also handle will-change appropriately.
   return StyleDisplay()->IsPositionedStyle() &&
-         !mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame);
+         !aContextFrame->IsInSVGTextSubtree();
 }
 
 }  // namespace mozilla
diff --git a/layout/style/nsFontFaceUtils.cpp b/layout/style/nsFontFaceUtils.cpp
index ea608ee2c055..060dbe7ed0a8 100644
--- a/layout/style/nsFontFaceUtils.cpp
+++ b/layout/style/nsFontFaceUtils.cpp
@@ -10,7 +10,6 @@
 #include "gfxUserFontSet.h"
 #include "mozilla/PresShell.h"
 #include "mozilla/RestyleManager.h"
-#include "mozilla/SVGUtils.h"
 #include "nsFontMetrics.h"
 #include "nsIFrame.h"
 #include "nsLayoutUtils.h"
@@ -125,7 +124,7 @@ static FontUsageKind FrameFontUsage(nsIFrame* aFrame,
 // TODO(emilio): Can we use the restyle-hint machinery instead of this?
 static void ScheduleReflow(PresShell* aPresShell, nsIFrame* aFrame) {
   nsIFrame* f = aFrame;
-  if (f->IsFrameOfType(nsIFrame::eSVG) || SVGUtils::IsInSVGTextSubtree(f)) {
+  if (f->IsFrameOfType(nsIFrame::eSVG) || f->IsInSVGTextSubtree()) {
     // SVG frames (and the non-SVG descendants of an SVGTextFrame) need special
     // reflow handling.  We need to search upwards for the first displayed
     // SVGOuterSVGFrame or non-SVG frame, which is the frame we can call
@@ -142,7 +141,7 @@ static void ScheduleReflow(PresShell* aPresShell, nsIFrame* aFrame) {
             return;
           }
           if (!f->HasAnyStateBits(NS_FRAME_SVG_LAYOUT) ||
-              !SVGUtils::IsInSVGTextSubtree(f)) {
+              !f->IsInSVGTextSubtree()) {
             break;
           }
           f->AddStateBits(NS_FRAME_HAS_DIRTY_CHILDREN);
diff --git a/layout/style/nsStyleStructInlines.h b/layout/style/nsStyleStructInlines.h
index a15298a83de6..cd2265c4b92b 100644
--- a/layout/style/nsStyleStructInlines.h
+++ b/layout/style/nsStyleStructInlines.h
@@ -14,9 +14,8 @@
 
 #include "nsIFrame.h"
 #include "nsStyleStruct.h"
-#include "nsIContent.h"        // for GetParent()
-#include "nsTextFrame.h"       // for nsTextFrame::ShouldSuppressLineBreak
-#include "mozilla/SVGUtils.h"  // for SVGUtils::IsInSVGTextSubtree
+#include "nsIContent.h"   // for GetParent()
+#include "nsTextFrame.h"  // for nsTextFrame::ShouldSuppressLineBreak
 
 bool nsStyleText::NewlineIsSignificant(const nsTextFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleText() == this, "unexpected aContextFrame");
@@ -27,21 +26,19 @@ bool nsStyleText::NewlineIsSignificant(const nsTextFrame* aContextFrame) const {
 
 bool nsStyleText::WhiteSpaceCanWrap(const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleText() == this, "unexpected aContextFrame");
-  return WhiteSpaceCanWrapStyle() &&
-         !mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame) &&
+  return WhiteSpaceCanWrapStyle() && !aContextFrame->IsInSVGTextSubtree() &&
          !aContextFrame->Style()->IsTextCombined();
 }
 
 bool nsStyleText::WordCanWrap(const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleText() == this, "unexpected aContextFrame");
-  return WordCanWrapStyle() &&
-         !mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame);
+  return WordCanWrapStyle() && !aContextFrame->IsInSVGTextSubtree();
 }
 
 bool nsStyleDisplay::IsBlockOutside(const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleDisplay() == this,
                "unexpected aContextFrame");
-  if (mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame)) {
+  if (aContextFrame->IsInSVGTextSubtree()) {
     return aContextFrame->IsBlockFrame();
   }
   return IsBlockOutsideStyle();
@@ -50,7 +47,7 @@ bool nsStyleDisplay::IsBlockOutside(const nsIFrame* aContextFrame) const {
 bool nsStyleDisplay::IsInlineOutside(const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleDisplay() == this,
                "unexpected aContextFrame");
-  if (mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame)) {
+  if (aContextFrame->IsInSVGTextSubtree()) {
     return !aContextFrame->IsBlockFrame();
   }
   return IsInlineOutsideStyle();
@@ -60,7 +57,7 @@ mozilla::StyleDisplay nsStyleDisplay::GetDisplay(
     const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleDisplay() == this,
                "unexpected aContextFrame");
-  if (mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame) &&
+  if (aContextFrame->IsInSVGTextSubtree() &&
       mDisplay != mozilla::StyleDisplay::None) {
     return aContextFrame->IsBlockFrame() ? mozilla::StyleDisplay::Block
                                          : mozilla::StyleDisplay::Inline;
@@ -71,8 +68,7 @@ mozilla::StyleDisplay nsStyleDisplay::GetDisplay(
 bool nsStyleDisplay::IsFloating(const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleDisplay() == this,
                "unexpected aContextFrame");
-  return IsFloatingStyle() &&
-         !mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame);
+  return IsFloatingStyle() && !aContextFrame->IsInSVGTextSubtree();
 }
 
 // If you change this function, also change the corresponding block in
@@ -110,30 +106,27 @@ bool nsStyleDisplay::IsRelativelyOrStickyPositioned(
   NS_ASSERTION(aContextFrame->StyleDisplay() == this,
                "unexpected aContextFrame");
   return IsRelativelyOrStickyPositionedStyle() &&
-         !mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame);
+         !aContextFrame->IsInSVGTextSubtree();
 }
 
 bool nsStyleDisplay::IsRelativelyPositioned(
     const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleDisplay() == this,
                "unexpected aContextFrame");
-  return IsRelativelyPositionedStyle() &&
-         !mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame);
+  return IsRelativelyPositionedStyle() && !aContextFrame->IsInSVGTextSubtree();
 }
 
 bool nsStyleDisplay::IsStickyPositioned(const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleDisplay() == this,
                "unexpected aContextFrame");
-  return IsStickyPositionedStyle() &&
-         !mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame);
+  return IsStickyPositionedStyle() && !aContextFrame->IsInSVGTextSubtree();
 }
 
 bool nsStyleDisplay::IsAbsolutelyPositioned(
     const nsIFrame* aContextFrame) const {
   NS_ASSERTION(aContextFrame->StyleDisplay() == this,
                "unexpected aContextFrame");
-  return IsAbsolutelyPositionedStyle() &&
-         !mozilla::SVGUtils::IsInSVGTextSubtree(aContextFrame);
+  return IsAbsolutelyPositionedStyle() && !aContextFrame->IsInSVGTextSubtree();
 }
 
 bool nsStyleBackground::HasLocalBackground() const {
diff --git a/layout/svg/SVGObserverUtils.cpp b/layout/svg/SVGObserverUtils.cpp
index 0df0d76e39e1..7108999f8bd7 100644
--- a/layout/svg/SVGObserverUtils.cpp
+++ b/layout/svg/SVGObserverUtils.cpp
@@ -494,9 +494,9 @@ void SVGTextPathObserver::OnRenderingChange() {
     return;
   }
 
-  MOZ_ASSERT(frame->IsFrameOfType(nsIFrame::eSVG) ||
-                 SVGUtils::IsInSVGTextSubtree(frame),
-             "SVG frame expected");
+  MOZ_ASSERT(
+      frame->IsFrameOfType(nsIFrame::eSVG) || frame->IsInSVGTextSubtree(),
+      "SVG frame expected");
 
   MOZ_ASSERT(frame->GetContent()->IsSVGElement(nsGkAtoms::textPath),
              "expected frame for a <textPath> element");
diff --git a/layout/svg/SVGUtils.cpp b/layout/svg/SVGUtils.cpp
index 6c6a33c3a3c9..3bf7e0bd5716 100644
--- a/layout/svg/SVGUtils.cpp
+++ b/layout/svg/SVGUtils.cpp
@@ -105,7 +105,7 @@ bool SVGAutoRenderState::IsPaintingToWindow(DrawTarget* aDrawTarget) {
 // GetCanvasTM().
 static bool FrameDoesNotIncludePositionInTM(const nsIFrame* aFrame) {
   return aFrame->IsSVGGeometryFrame() || aFrame->IsSVGImageFrame() ||
-         SVGUtils::IsInSVGTextSubtree(aFrame);
+         aFrame->IsInSVGTextSubtree();
 }
 
 nsRect SVGUtils::GetPostFilterInkOverflowRect(nsIFrame* aFrame,
@@ -394,9 +394,9 @@ void SVGUtils::NotifyChildrenOfSVGChange(nsIFrame* aFrame, uint32_t aFlags) {
     if (SVGFrame) {
       SVGFrame->NotifySVGChanged(aFlags);
     } else {
-      NS_ASSERTION(kid->IsFrameOfType(nsIFrame::eSVG) ||
-                       SVGUtils::IsInSVGTextSubtree(kid),
-                   "SVG frame expected");
+      NS_ASSERTION(
+          kid->IsFrameOfType(nsIFrame::eSVG) || kid->IsInSVGTextSubtree(),
+          "SVG frame expected");
       // recurse into the children of container frames e.g. <clipPath>, <mask>
       // in case they have child frames with transformation matrices
       if (kid->IsFrameOfType(nsIFrame::eSVG)) {
@@ -985,7 +985,7 @@ gfxRect SVGUtils::GetBBox(nsIFrame* aFrame, uint32_t aFlags,
     aFrame = aFrame->GetParent();
   }
 
-  if (SVGUtils::IsInSVGTextSubtree(aFrame)) {
+  if (aFrame->IsInSVGTextSubtree()) {
     // It is possible to apply a gradient, pattern, clipping path, mask or
     // filter to text. When one of these facilities is applied to text
     // the bounding box is the entire text element in all cases.
@@ -1263,7 +1263,7 @@ static gfxRect PathExtentsToMaxStrokeExtents(const gfxRect& aPathExtents,
 gfxRect SVGUtils::PathExtentsToMaxStrokeExtents(const gfxRect& aPathExtents,
                                                 const nsTextFrame* aFrame,
                                                 const gfxMatrix& aMatrix) {
-  NS_ASSERTION(SVGUtils::IsInSVGTextSubtree(aFrame),
+  NS_ASSERTION(aFrame->IsInSVGTextSubtree(),
                "expected an nsTextFrame for SVG text");
   return mozilla::PathExtentsToMaxStrokeExtents(aPathExtents, aFrame, 0.5,
                                                 aMatrix);
diff --git a/layout/svg/SVGUtils.h b/layout/svg/SVGUtils.h
index 6f9924cd4253..2458d0a538f4 100644
--- a/layout/svg/SVGUtils.h
+++ b/layout/svg/SVGUtils.h
@@ -588,11 +588,6 @@ class SVGUtils final {
    */
   static gfxMatrix GetCSSPxToDevPxMatrix(const nsIFrame* aNonSVGFrame);
 
-  static bool IsInSVGTextSubtree(const nsIFrame* aFrame) {
-    // Returns true if the frame is an SVGTextFrame or one of its descendants.
-    return aFrame->HasAnyStateBits(NS_FRAME_IS_SVG_TEXT);
-  }
-
   /**
    * It is a replacement of
    * SVGElement::PrependLocalTransformsTo(eUserSpaceToParent).