Refactor RenderQuote to not delete renderers on style change.

Source/core/rendering/RenderQuote.cpp

 /**
  * Copyright (C) 2011 Nokia Inc.  All rights reserved.
  * Copyright (C) 2012 Google 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 252 matching lines @@
 }
 
 void RenderQuote::updateText()
 {
     String text = computeText();
     if (m_text == text)
         return;
 
     m_text = text;
 
-    while (RenderObject* child = lastChild())
-        child->destroy();
+    RenderTextFragment* fragment = findFragmentChild();
+    if (fragment) {
+        fragment->setStyle(style());
+        fragment->setContentString(m_text.impl());
+    } else {
+        fragment = new RenderTextFragment(&document(), m_text.impl());
+        fragment->setStyle(style());
+        addChild(fragment);
+    }
+}
 
-    RenderTextFragment* fragment = new RenderTextFragment(&document(), m_text.impl());
-    fragment->setStyle(style());
-    addChild(fragment);
+RenderTextFragment* RenderQuote::findFragmentChild() const
+{
+    // We walk from the end of the child list because, if we've had a first-letter
+    // renderer inserted then the remaining text will be at the end.
+    while (RenderObject* child = lastChild()) {
+        if (child->isText() && toRenderText(child)->isTextFragment())
+            return toRenderTextFragment(child);
+    }
+
+    return nullptr;
 }
 
 String RenderQuote::computeText() const
 {
     switch (m_type) {
     case NO_OPEN_QUOTE:
     case NO_CLOSE_QUOTE:
         return emptyString();
     case CLOSE_QUOTE:
         return quotesData()->getCloseQuote(m_depth - 1).impl();
@@ skipping 97 matching lines @@
             if (m_depth)
                 m_depth--;
             break;
         }
     }
     if (oldDepth != m_depth)
         updateText();
 }
 
 } // namespace blink