Replace custom code by hasOneTextChild API

Source/core/html/HTMLOptionElement.cpp

Index: Source/core/html/HTMLOptionElement.cpp
diff --git a/Source/core/html/HTMLOptionElement.cpp b/Source/core/html/HTMLOptionElement.cpp
index 1bdde70b90d434be260de3938d7652317c9ab16a..c7ad4391cab026abc0592ebade6085088d0580a6 100644
--- a/Source/core/html/HTMLOptionElement.cpp
+++ b/Source/core/html/HTMLOptionElement.cpp
@@ -133,9 +133,8 @@ void HTMLOptionElement::setText(const String &text, ExceptionState& exceptionSta
     int oldSelectedIndex = selectIsMenuList ? select->selectedIndex() : -1;
 
     // Handle the common special case where there's exactly 1 child node, and it's a text node.

[adamk, 2014/11/04 00:56:56]

This comment is now very redundant with the code, please remove while you're at
it.

-    Node* child = firstChild();
-    if (child && child->isTextNode() && !child->nextSibling())
-        toText(child)->setData(text);
+    if (hasOneTextChild())
+        toText(firstChild())->setData(text);
     else {
         removeChildren();
         appendChild(Text::create(document(), text), exceptionState);