Collapse whitespace away when creating whitespace layout objects.

third_party/WebKit/Source/core/dom/Text.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights
  * reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 234 matching lines @@
 
   if (parent.isTable() || parent.isTableRow() || parent.isTableSection() ||
       parent.isLayoutTableCol() || parent.isFrameSet() ||
       parent.isFlexibleBox() || parent.isLayoutGrid() || parent.isSVGRoot() ||
       parent.isSVGContainer() || parent.isSVGImage() || parent.isSVGShape()) {
     return false;
   }
   return true;
 }
 
+static inline bool emptyOrEndsWithWhitespace(const WTF::String& string) {
+  unsigned len = string.length();
+  return !len || isASCIISpace(string[len - 1]);
+}
+
 bool Text::textLayoutObjectIsNeeded(const ComputedStyle& style,
                                     const LayoutObject& parent) const {
   DCHECK(!document().childNeedsDistributionRecalc());
 
   if (!parent.canHaveChildren())
     return false;
 
   if (isEditingText())
     return true;
 
@@ skipping 18 matching lines @@
     return true;
 
   // Avoiding creation of a layoutObject for the text node is a non-essential
   // memory optimization.  So to avoid blowing up on very wide DOMs, we limit
   // the number of siblings to visit.
   unsigned maxSiblingsToVisit = 50;
 
   const LayoutObject* prev =
       LayoutTreeBuilderTraversal::previousSiblingLayoutObject(
           *this, maxSiblingsToVisit);
+
+  while (prev && prev->isOutOfFlowPositioned() && --maxSiblingsToVisit)
+    prev = prev->previousSibling();
+
+  if (!maxSiblingsToVisit)
+    return true;
+
   if (prev && prev->isBR())  // <span><br/> <br/></span>
     return false;
 
+  // Collapse whitespace away.
+  if (prev && prev->isText() &&
+      emptyOrEndsWithWhitespace(toLayoutText(prev)->text()))
+    return false;
+
   if (parent.isLayoutInline()) {
     // <span><div/> <div/></span>
     if (prev && !prev->isInline() && !prev->isOutOfFlowPositioned())

[rune, 2017/02/28 09:59:46]

prev cannot be out-of-flow at this point since prev is not modified after the
while-loop you added.

       return false;
   } else {
     if (parent.isLayoutBlock() && !parent.childrenInline() &&
         (!prev || !prev->isInline()))
       return false;
 
     LayoutObject* first = parent.slowFirstChild();
     for (; first && first->isFloatingOrOutOfFlowPositioned() &&
            maxSiblingsToVisit;
          first = first->nextSibling(), --maxSiblingsToVisit) {
@@ skipping 158 matching lines @@
 
 Text* Text::cloneWithData(const String& data) {
   return create(document(), data);
 }
 
 DEFINE_TRACE(Text) {
   CharacterData::trace(visitor);
 }
 
 }  // namespace blink