Bug 1646639 - Don't recursively apply the line's start-offset and text-indent to children of a first-line frame. r=dholbert

But do apply any adjustment needed for text-align to the first-line frame itself.

Differential Revision: https://phabricator.services.mozilla.com/D82725

layout/base/nsBidiPresUtils.cpp

@@ -1486,6 +1486,9 @@ nscoord nsBidiPresUtils::ReorderFrames(nsIFrame* aFirstFrameOnLine,
     // aNumFramesOnLine to -1 makes InitLogicalArrayFromLine look at all of
     // them.
     aNumFramesOnLine = -1;
+    // As the line frame itself has been adjusted at its inline-start position
+    // by the caller, we do not want to apply this to its children.
+    aStart = 0;
   }
 
   BidiLineData bld(aFirstFrameOnLine, aNumFramesOnLine);

layout/generic/nsLineLayout.cpp

@@ -3186,6 +3186,14 @@ void nsLineLayout::TextAlignLine(nsLineBox* aLine, bool aIsLastLine) {
                                    lineWM, mContainerSize,
                                    psd->mIStart + mTextIndent + dx);
     if (dx) {
+      if (startFrame->mFrame->IsLineFrame()) {
+        // If startFrame is a ::first-line frame, the mIStart and mTextIndent
+        // offsets will already have been applied to its position. But we still
+        // need to apply the text-align adjustment |dx| to its position.
+        startFrame->mBounds.IStart(lineWM) += dx;
+        startFrame->mFrame->SetRect(lineWM, startFrame->mBounds,
+                                    ContainerSizeForSpan(psd));
+      }
       aLine->IndentBy(dx, ContainerSize());
     }
   } else if (dx) {

testing/web-platform/meta/css/selectors/floating-first-letter-05d0.html.ini

@@ -1,4 +0,0 @@
-[floating-first-letter-05d0.html]
-  type: reftest
-  expected: FAIL
-  bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1495674