Fieldset should allow whitespaces even though LayoutFlexibleBox doesn't.

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 225 matching lines @@
     return kTextNode;
 }
 
 Node* Text::cloneNode(bool /*deep*/)
 {
     return cloneWithData(data());
 }
 
 static inline bool canHaveWhitespaceChildren(const LayoutObject& parent)
 {
-    // <button> should allow whitespace even though LayoutFlexibleBox doesn't.
-    if (parent.isLayoutButton())
+    // <button> and <fieldset> should allow whitespace even though
+    // LayoutFlexibleBox doesn't.
+    if (parent.isLayoutButton() || parent.isFieldset())
         return true;
 
     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;
@@ skipping 180 matching lines @@
 {
     return create(document(), data);
 }
 
 DEFINE_TRACE(Text)
 {
     CharacterData::trace(visitor);
 }
 
 } // namespace blink