diff --git a/dom/events/EventStateManager.cpp b/dom/events/EventStateManager.cpp
index e3472323bca0..20b1bc8ef18d 100644
--- a/dom/events/EventStateManager.cpp
+++ b/dom/events/EventStateManager.cpp
@@ -3022,7 +3022,7 @@ EventStateManager::PostHandleEvent(nsPresContext* aPresContext,
           // If the mousedown happened inside a popup, don't
           // try to set focus on one of its containing elements
           const nsStyleDisplay* display = currFrame->StyleDisplay();
-          if (display->mDisplay == StyleDisplay::Popup) {
+          if (display->mDisplay == StyleDisplay::MozPopup) {
             newFocus = nullptr;
             break;
           }
diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 73f94c0cb34f..213c6ce1f5d7 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -4293,20 +4293,20 @@ nsCSSFrameConstructor::GetAnonymousContent(nsIContent* aParent,
 static
 bool IsXULDisplayType(const nsStyleDisplay* aDisplay)
 {
-  return (aDisplay->mDisplay == StyleDisplay::InlineBox ||
+  return (aDisplay->mDisplay == StyleDisplay::MozInlineBox ||
 #ifdef MOZ_XUL
-          aDisplay->mDisplay == StyleDisplay::InlineXulGrid ||
-          aDisplay->mDisplay == StyleDisplay::InlineStack ||
+          aDisplay->mDisplay == StyleDisplay::MozInlineGrid ||
+          aDisplay->mDisplay == StyleDisplay::MozInlineStack ||
 #endif
-          aDisplay->mDisplay == StyleDisplay::Box
+          aDisplay->mDisplay == StyleDisplay::MozBox
 #ifdef MOZ_XUL
-          || aDisplay->mDisplay == StyleDisplay::XulGrid ||
-          aDisplay->mDisplay == StyleDisplay::Stack ||
-          aDisplay->mDisplay == StyleDisplay::XulGridGroup ||
-          aDisplay->mDisplay == StyleDisplay::XulGridLine ||
-          aDisplay->mDisplay == StyleDisplay::Deck ||
-          aDisplay->mDisplay == StyleDisplay::Popup ||
-          aDisplay->mDisplay == StyleDisplay::Groupbox
+          || aDisplay->mDisplay == StyleDisplay::MozGrid ||
+          aDisplay->mDisplay == StyleDisplay::MozStack ||
+          aDisplay->mDisplay == StyleDisplay::MozGridGroup ||
+          aDisplay->mDisplay == StyleDisplay::MozGridLine ||
+          aDisplay->mDisplay == StyleDisplay::MozDeck ||
+          aDisplay->mDisplay == StyleDisplay::MozPopup ||
+          aDisplay->mDisplay == StyleDisplay::MozGroupbox
 #endif
           );
 }
@@ -4485,7 +4485,7 @@ nsCSSFrameConstructor::FindXULListBoxBodyData(Element* aElement,
                                               nsStyleContext* aStyleContext)
 {
   if (aStyleContext->StyleDisplay()->mDisplay !=
-        StyleDisplay::XulGridGroup) {
+        StyleDisplay::MozGridGroup) {
     return nullptr;
   }
 
@@ -4499,7 +4499,7 @@ const nsCSSFrameConstructor::FrameConstructionData*
 nsCSSFrameConstructor::FindXULListItemData(Element* aElement,
                                            nsStyleContext* aStyleContext)
 {
-  if (aStyleContext->StyleDisplay()->mDisplay != StyleDisplay::XulGridLine) {
+  if (aStyleContext->StyleDisplay()->mDisplay != StyleDisplay::MozGridLine) {
     return nullptr;
   }
 
@@ -4517,36 +4517,36 @@ nsCSSFrameConstructor::FindXULDisplayData(const nsStyleDisplay* aDisplay,
                                           nsStyleContext* aStyleContext)
 {
   static const FrameConstructionDataByDisplay sXULDisplayData[] = {
-    SCROLLABLE_ABSPOS_CONTAINER_XUL_DISPLAY_CREATE(StyleDisplay::Box,
+    SCROLLABLE_ABSPOS_CONTAINER_XUL_DISPLAY_CREATE(StyleDisplay::MozBox,
                                                    NS_NewBoxFrame),
-    SCROLLABLE_ABSPOS_CONTAINER_XUL_DISPLAY_CREATE(StyleDisplay::InlineBox,
+    SCROLLABLE_ABSPOS_CONTAINER_XUL_DISPLAY_CREATE(StyleDisplay::MozInlineBox,
                                                    NS_NewBoxFrame),
 #ifdef MOZ_XUL
-    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::XulGrid, NS_NewGridBoxFrame),
-    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::InlineXulGrid, NS_NewGridBoxFrame),
-    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::XulGridGroup,
+    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::MozGrid, NS_NewGridBoxFrame),
+    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::MozInlineGrid, NS_NewGridBoxFrame),
+    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::MozGridGroup,
                                   NS_NewGridRowGroupFrame),
-    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::XulGridLine,
+    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::MozGridLine,
                                   NS_NewGridRowLeafFrame),
-    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::Stack, NS_NewStackFrame),
-    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::InlineStack, NS_NewStackFrame),
-    SIMPLE_XUL_DISPLAY_CREATE(StyleDisplay::Deck, NS_NewDeckFrame),
-    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::Groupbox, NS_NewGroupBoxFrame),
-    FCDATA_FOR_DISPLAY(StyleDisplay::Popup,
+    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::MozStack, NS_NewStackFrame),
+    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::MozInlineStack, NS_NewStackFrame),
+    SIMPLE_XUL_DISPLAY_CREATE(StyleDisplay::MozDeck, NS_NewDeckFrame),
+    SCROLLABLE_XUL_DISPLAY_CREATE(StyleDisplay::MozGroupbox, NS_NewGroupBoxFrame),
+    FCDATA_FOR_DISPLAY(StyleDisplay::MozPopup,
       FCDATA_DECL(FCDATA_DISALLOW_OUT_OF_FLOW | FCDATA_IS_POPUP |
                   FCDATA_SKIP_ABSPOS_PUSH, NS_NewMenuPopupFrame))
 #endif /* MOZ_XUL */
   };
 
-  if (aDisplay->mDisplay < StyleDisplay::Box) {
+  if (aDisplay->mDisplay < StyleDisplay::MozBox) {
     return nullptr;
   }
 
-  MOZ_ASSERT(aDisplay->mDisplay <= StyleDisplay::Popup,
+  MOZ_ASSERT(aDisplay->mDisplay <= StyleDisplay::MozPopup,
              "Someone added a new display value?");
 
   const FrameConstructionDataByDisplay& data =
-    sXULDisplayData[size_t(aDisplay->mDisplay) - size_t(StyleDisplay::Box)];
+    sXULDisplayData[size_t(aDisplay->mDisplay) - size_t(StyleDisplay::MozBox)];
   MOZ_ASSERT(aDisplay->mDisplay == data.mDisplay,
              "Did someone mess with the order?");
 
@@ -4576,8 +4576,8 @@ nsCSSFrameConstructor::BeginBuildingScrollFrame(nsFrameConstructorState& aState,
     const nsStyleDisplay* displayStyle = aContentStyle->StyleDisplay();
     if (IsXULDisplayType(displayStyle)) {
       gfxScrollFrame = NS_NewXULScrollFrame(mPresShell, contentStyle, aIsRoot,
-          displayStyle->mDisplay == StyleDisplay::Stack ||
-          displayStyle->mDisplay == StyleDisplay::InlineStack);
+          displayStyle->mDisplay == StyleDisplay::MozStack ||
+          displayStyle->mDisplay == StyleDisplay::MozInlineStack);
     } else {
       gfxScrollFrame = NS_NewHTMLScrollFrame(mPresShell, contentStyle, aIsRoot);
     }
@@ -6613,8 +6613,8 @@ nsCSSFrameConstructor::IsValidSibling(nsIFrame*              aSibling,
     }
     if (nsGkAtoms::menuFrame == parentType) {
       return
-        (StyleDisplay::Popup == aDisplay) ==
-        (StyleDisplay::Popup == siblingDisplay);
+        (StyleDisplay::MozPopup == aDisplay) ==
+        (StyleDisplay::MozPopup == siblingDisplay);
     }
     // To have decent performance we want to return false in cases in which
     // reordering the two siblings has no effect on display.  To ensure
@@ -10902,7 +10902,7 @@ nsCSSFrameConstructor::ProcessChildren(nsFrameConstructorState& aState,
       const char16_t* params[] = { parentTag.get(), kidTag.get() };
       const nsStyleDisplay *display = frameStyleContext->StyleDisplay();
       const char *message =
-        (display->mDisplay == StyleDisplay::InlineBox)
+        (display->mDisplay == StyleDisplay::MozInlineBox)
           ? "NeededToWrapXULInlineBox" : "NeededToWrapXUL";
       nsContentUtils::ReportToConsole(nsIScriptError::warningFlag,
                                       NS_LITERAL_CSTRING("Layout: FrameConstructor"),
diff --git a/layout/base/nsFrameTraversal.cpp b/layout/base/nsFrameTraversal.cpp
index 40fb5ff30c03..6d444c24a2d0 100644
--- a/layout/base/nsFrameTraversal.cpp
+++ b/layout/base/nsFrameTraversal.cpp
@@ -509,7 +509,7 @@ nsFrameIterator::IsPopupFrame(nsIFrame* aFrame)
   }
 
   return (aFrame &&
-          aFrame->StyleDisplay()->mDisplay == StyleDisplay::Popup);
+          aFrame->StyleDisplay()->mDisplay == StyleDisplay::MozPopup);
 }
 
 // nsVisualIterator implementation
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index b06c2b740b46..5b41aff30c41 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -1407,7 +1407,7 @@ nsLayoutUtils::GetChildListNameFor(nsIFrame* aChildFrame)
         id = nsIFrame::kAbsoluteList;
       }
 #ifdef MOZ_XUL
-    } else if (StyleDisplay::Popup == disp->mDisplay) {
+    } else if (StyleDisplay::MozPopup == disp->mDisplay) {
       // Out-of-flows that are DISPLAY_POPUP must be kids of the root popup set
 #ifdef DEBUG
       nsIFrame* parent = aChildFrame->GetParent();
diff --git a/layout/generic/ReflowInput.cpp b/layout/generic/ReflowInput.cpp
index f747f0954278..dc31b8f4208c 100644
--- a/layout/generic/ReflowInput.cpp
+++ b/layout/generic/ReflowInput.cpp
@@ -838,7 +838,7 @@ ReflowInput::InitFrameType(nsIAtom* aFrameType)
     else if (disp->IsFloating(mFrame)) {
       frameType = NS_CSS_FRAME_TYPE_FLOATING;
     } else {
-      NS_ASSERTION(disp->mDisplay == StyleDisplay::Popup,
+      NS_ASSERTION(disp->mDisplay == StyleDisplay::MozPopup,
                    "unknown out of flow frame type");
       frameType = NS_CSS_FRAME_TYPE_UNKNOWN;
     }
@@ -859,9 +859,9 @@ ReflowInput::InitFrameType(nsIAtom* aFrameType)
     case StyleDisplay::Inline:
     case StyleDisplay::InlineBlock:
     case StyleDisplay::InlineTable:
-    case StyleDisplay::InlineBox:
-    case StyleDisplay::InlineXulGrid:
-    case StyleDisplay::InlineStack:
+    case StyleDisplay::MozInlineBox:
+    case StyleDisplay::MozInlineGrid:
+    case StyleDisplay::MozInlineStack:
     case StyleDisplay::InlineFlex:
     case StyleDisplay::WebkitInlineBox:
     case StyleDisplay::InlineGrid:
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index badc56640be3..aa6d3064f5f6 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -1302,18 +1302,18 @@ KTableEntry nsCSSProps::kDisplayKTable[] = {
   { eCSSKeyword_table_caption,       StyleDisplay::TableCaption },
   // Make sure this is kept in sync with the code in
   // nsCSSFrameConstructor::ConstructXULFrame
-  { eCSSKeyword__moz_box,            StyleDisplay::Box },
-  { eCSSKeyword__moz_inline_box,     StyleDisplay::InlineBox },
+  { eCSSKeyword__moz_box,            StyleDisplay::MozBox },
+  { eCSSKeyword__moz_inline_box,     StyleDisplay::MozInlineBox },
 #ifdef MOZ_XUL
-  { eCSSKeyword__moz_grid,           StyleDisplay::XulGrid },
-  { eCSSKeyword__moz_inline_grid,    StyleDisplay::InlineXulGrid },
-  { eCSSKeyword__moz_grid_group,     StyleDisplay::XulGridGroup },
-  { eCSSKeyword__moz_grid_line,      StyleDisplay::XulGridLine },
-  { eCSSKeyword__moz_stack,          StyleDisplay::Stack },
-  { eCSSKeyword__moz_inline_stack,   StyleDisplay::InlineStack },
-  { eCSSKeyword__moz_deck,           StyleDisplay::Deck },
-  { eCSSKeyword__moz_popup,          StyleDisplay::Popup },
-  { eCSSKeyword__moz_groupbox,       StyleDisplay::Groupbox },
+  { eCSSKeyword__moz_grid,           StyleDisplay::MozGrid },
+  { eCSSKeyword__moz_inline_grid,    StyleDisplay::MozInlineGrid },
+  { eCSSKeyword__moz_grid_group,     StyleDisplay::MozGridGroup },
+  { eCSSKeyword__moz_grid_line,      StyleDisplay::MozGridLine },
+  { eCSSKeyword__moz_stack,          StyleDisplay::MozStack },
+  { eCSSKeyword__moz_inline_stack,   StyleDisplay::MozInlineStack },
+  { eCSSKeyword__moz_deck,           StyleDisplay::MozDeck },
+  { eCSSKeyword__moz_popup,          StyleDisplay::MozPopup },
+  { eCSSKeyword__moz_groupbox,       StyleDisplay::MozGroupbox },
 #endif
   { eCSSKeyword_flex,                StyleDisplay::Flex },
   { eCSSKeyword_inline_flex,         StyleDisplay::InlineFlex },
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 9fda3c5ddda2..1df0741f2154 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -289,11 +289,11 @@ nsRuleNode::EnsureInlineDisplay(StyleDisplay& display)
     case StyleDisplay::Grid:
       display = StyleDisplay::InlineGrid;
       break;
-    case StyleDisplay::Box:
-      display = StyleDisplay::InlineBox;
+    case StyleDisplay::MozBox:
+      display = StyleDisplay::MozInlineBox;
       break;
-    case StyleDisplay::Stack:
-      display = StyleDisplay::InlineStack;
+    case StyleDisplay::MozStack:
+      display = StyleDisplay::MozInlineStack;
       break;
     default:
       break; // Do nothing
@@ -1445,7 +1445,7 @@ struct SetEnumValueHelper
   DEFINE_ENUM_CLASS_SETTER(StyleWindowDragging, Default, NoDrag)
   DEFINE_ENUM_CLASS_SETTER(StyleOrient, Inline, Vertical)
 #ifdef MOZ_XUL
-  DEFINE_ENUM_CLASS_SETTER(StyleDisplay, None, Popup)
+  DEFINE_ENUM_CLASS_SETTER(StyleDisplay, None, MozPopup)
 #else
   DEFINE_ENUM_CLASS_SETTER(StyleDisplay, None, InlineBox)
 #endif
diff --git a/layout/style/nsStyleConsts.h b/layout/style/nsStyleConsts.h
index 87328e08e05d..dde88b2f490f 100644
--- a/layout/style/nsStyleConsts.h
+++ b/layout/style/nsStyleConsts.h
@@ -514,18 +514,18 @@ enum class StyleDisplay : uint8_t {
   Contents,
   WebkitBox,
   WebkitInlineBox,
-  Box,
-  InlineBox,
+  MozBox,
+  MozInlineBox,
 #ifdef MOZ_XUL
-  XulGrid,
-  InlineXulGrid,
-  XulGridGroup,
-  XulGridLine,
-  Stack,
-  InlineStack,
-  Deck,
-  Groupbox,
-  Popup,
+  MozGrid,
+  MozInlineGrid,
+  MozGridGroup,
+  MozGridLine,
+  MozStack,
+  MozInlineStack,
+  MozDeck,
+  MozGroupbox,
+  MozPopup,
 #endif
 };
 
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index a8c64c77c0c7..f87166be7a20 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -2904,12 +2904,12 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleDisplay
     return mozilla::StyleDisplay::Inline == aDisplay ||
            mozilla::StyleDisplay::InlineBlock == aDisplay ||
            mozilla::StyleDisplay::InlineTable == aDisplay ||
-           mozilla::StyleDisplay::InlineBox == aDisplay ||
+           mozilla::StyleDisplay::MozInlineBox == aDisplay ||
            mozilla::StyleDisplay::InlineFlex == aDisplay ||
            mozilla::StyleDisplay::WebkitInlineBox == aDisplay ||
            mozilla::StyleDisplay::InlineGrid == aDisplay ||
-           mozilla::StyleDisplay::InlineXulGrid == aDisplay ||
-           mozilla::StyleDisplay::InlineStack == aDisplay ||
+           mozilla::StyleDisplay::MozInlineGrid == aDisplay ||
+           mozilla::StyleDisplay::MozInlineStack == aDisplay ||
            mozilla::StyleDisplay::Ruby == aDisplay ||
            mozilla::StyleDisplay::RubyBase == aDisplay ||
            mozilla::StyleDisplay::RubyBaseContainer == aDisplay ||
diff --git a/layout/xul/nsBoxFrame.cpp b/layout/xul/nsBoxFrame.cpp
index 9ca351d94526..01764d03cbff 100644
--- a/layout/xul/nsBoxFrame.cpp
+++ b/layout/xul/nsBoxFrame.cpp
@@ -1237,7 +1237,7 @@ nsBoxFrame::AttributeChanged(int32_t aNameSpaceID,
     // kPopupList and XULRelayoutChildAtOrdinal() only handles
     // principal children.
     if (parent && !(GetStateBits() & NS_FRAME_OUT_OF_FLOW) &&
-        StyleDisplay()->mDisplay != mozilla::StyleDisplay::Popup) {
+        StyleDisplay()->mDisplay != mozilla::StyleDisplay::MozPopup) {
       parent->XULRelayoutChildAtOrdinal(this);
       // XXXldb Should this instead be a tree change on the child or parent?
       PresContext()->PresShell()->