Avoid hash table lookup for every attribute

Source/core/html/HTMLElement.cpp

Index: Source/core/html/HTMLElement.cpp
diff --git a/Source/core/html/HTMLElement.cpp b/Source/core/html/HTMLElement.cpp
index 7c61629b0903a8e83b01f3e062cd6c7a20cb956c..7883e45286368c478802cb40c5823f7f4625cd99 100644
--- a/Source/core/html/HTMLElement.cpp
+++ b/Source/core/html/HTMLElement.cpp
@@ -205,6 +205,9 @@ const AtomicString& HTMLElement::eventNameForAttributeName(const QualifiedName&
     if (!attrName.namespaceURI().isNull())
         return nullAtom;
 
+    if (!attrName.localName().startsWith("on", false))

[eseidel, 2014/04/14 05:48:20]

What does the false mean?  (Clearly we should make that an enum at some point.)

+        return nullAtom;
+
     typedef HashMap<AtomicString, AtomicString> StringToStringMap;
     DEFINE_STATIC_LOCAL(StringToStringMap, attributeNameToEventNameMap, ());
     if (!attributeNameToEventNameMap.size()) {