Inherit EventTarget interface instead of duplicating its code

Source/core/dom/MessagePort.h

Index: Source/core/dom/MessagePort.h
diff --git a/Source/core/dom/MessagePort.h b/Source/core/dom/MessagePort.h
index 5124eb29b229a5582b4286360dacebb1470f3143..a76ef3837dd27ab237ca135c130eec26e904065f 100644
--- a/Source/core/dom/MessagePort.h
+++ b/Source/core/dom/MessagePort.h
@@ -48,7 +48,7 @@ class ScriptExecutionContext;
 // The overwhelmingly common case is sending a single port, so handle that efficiently with an inline buffer of size 1.
 typedef Vector<RefPtr<MessagePort>, 1> MessagePortArray;
 
-class MessagePort : public RefCounted<MessagePort>, public ScriptWrappable, public EventTarget {
+class MessagePort : public EventTarget, public RefCounted<MessagePort>, public ScriptWrappable {
 public:
     static PassRefPtr<MessagePort> create(ScriptExecutionContext& scriptExecutionContext) { return adoptRef(new MessagePort(scriptExecutionContext)); }
     virtual ~MessagePort();