Node::setTextContent should avoid work when nothing changes

Source/core/editing/markup.cpp

Index: Source/core/editing/markup.cpp
diff --git a/Source/core/editing/markup.cpp b/Source/core/editing/markup.cpp
index f7240ebcdd02b76de91fe266e63a858ff9c5b6e0..e29f2ca9cc010433129589d80b4043c508d2d9e2 100644
--- a/Source/core/editing/markup.cpp
+++ b/Source/core/editing/markup.cpp
@@ -1006,11 +1006,13 @@ void replaceChildrenWithFragment(ContainerNode* container, PassRefPtr<DocumentFr
         return;
     }
 
+    // FIXME: This is wrong if containerNode->firstChild() has more than one ref!

[Julien - ping for review, 2014/03/18 22:55:55]

I am not sure I understand this comment. All references should point to the same
Node or is it something else?

     if (containerNode->hasOneTextChild() && fragment->hasOneTextChild()) {
         toText(containerNode->firstChild())->setData(toText(fragment->firstChild())->data());
         return;
     }
 
+    // FIXME: No need to replace the child it is a text node and its contents are already == text.
     if (containerNode->hasOneChild()) {
         containerNode->replaceChild(fragment, containerNode->firstChild(), exceptionState);
         return;
@@ -1027,13 +1029,16 @@ void replaceChildrenWithText(ContainerNode* container, const String& text, Excep
 
     ChildListMutationScope mutation(*containerNode);
 
+    // FIXME: This is wrong if containerNode->firstChild() has more than one ref!
     if (containerNode->hasOneTextChild()) {
         toText(containerNode->firstChild())->setData(text);
         return;
     }
 
+    // NOTE: This method currently always creates a text node, even if that text node will be empty.
     RefPtr<Text> textNode = Text::create(containerNode->document(), text);
 
+    // FIXME: No need to replace the child it is a text node and its contents are already == text.
     if (containerNode->hasOneChild()) {
         containerNode->replaceChild(textNode.release(), containerNode->firstChild(), exceptionState);
         return;