Refactor RenderQuote to not delete renderers on style change.

Source/core/rendering/RenderQuote.cpp

Index: Source/core/rendering/RenderQuote.cpp
diff --git a/Source/core/rendering/RenderQuote.cpp b/Source/core/rendering/RenderQuote.cpp
index 1048a8427c1fbbe3fff05c3c1363549ab33cc288..a9e81007ea3e2cef4eeb89f43062b04d8f3f30e7 100644
--- a/Source/core/rendering/RenderQuote.cpp
+++ b/Source/core/rendering/RenderQuote.cpp
@@ -270,12 +270,27 @@ void RenderQuote::updateText()
 
     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* 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);
+    }
 
-    RenderTextFragment* fragment = new RenderTextFragment(&document(), m_text.impl());
-    fragment->setStyle(style());
-    addChild(fragment);
+    return nullptr;
 }
 
 String RenderQuote::computeText() const