Search correctly for inline ancestors without a sibling when dirtying lineboxes

third_party/WebKit/Source/core/layout/line/LineBoxList.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 271 matching lines @@
       container.Parent().DirtyLinesFromChangedChild(container);
       // Mark the container to avoid dirtying the same lines again across
       // multiple destroy() calls of the same subtree.
       container.SetAncestorLineBoxDirty();
     }
     return;
   }
 
   // Try to figure out which line box we belong in. First try to find a previous
   // line box by examining our siblings. If we are a float inside an inline then
-  // check the siblings of our inline parent. If we didn't find a line box, then
-  // use our parent's first line box.
+  // check our nearest inline ancestor with siblings. If we didn't find a line
+  // box, then use our parent's first line box.
   RootInlineBox* box = nullptr;
   LineLayoutItem curr = child.PreviousSibling();
   if (child.IsFloating() && !curr) {
-    LineLayoutInline outer_inline;
-    for (LineLayoutItem parent = child.Parent();
-         parent && parent.IsLayoutInline() && !parent.PreviousSibling();
-         parent = parent.Parent())
-      outer_inline = LineLayoutInline(parent);
-    if (outer_inline)
-      curr = outer_inline.PreviousSibling();
+    DCHECK(child.Parent());
+    if (child.Parent().IsLayoutInline()) {
+      LineLayoutItem outer_inline = child.Parent();
+      while (outer_inline && !outer_inline.PreviousSibling() &&
+             outer_inline.Parent().IsLayoutInline())
+        outer_inline = outer_inline.Parent();
+      if (outer_inline)
+        curr = outer_inline.PreviousSibling();
+    }
   }
 
   for (; curr; curr = curr.PreviousSibling()) {
     if (curr.IsFloatingOrOutOfFlowPositioned())
       continue;
 
     if (curr.IsAtomicInlineLevel()) {
       InlineBox* wrapper = LineLayoutBox(curr).InlineBoxWrapper();
       if (wrapper)
         box = &wrapper->Root();
@@ skipping 62 matching lines @@
     DCHECK_EQ(child->prevLineBox(), prev);
     prev = child;
   }
   DCHECK_EQ(prev, m_lastLineBox);
 #endif
 }
 
 #endif
 
 }  // namespace blink