Inherit EventTarget interface instead of duplicating its code

Source/modules/speech/SpeechSynthesisUtterance.h

Index: Source/modules/speech/SpeechSynthesisUtterance.h
diff --git a/Source/modules/speech/SpeechSynthesisUtterance.h b/Source/modules/speech/SpeechSynthesisUtterance.h
index 211b96f7f3fbed9f39170c28bc6d65d38c6d5715..9f261e4d880ffc31a5538b734cd861afdd38965c 100644
--- a/Source/modules/speech/SpeechSynthesisUtterance.h
+++ b/Source/modules/speech/SpeechSynthesisUtterance.h
@@ -36,7 +36,7 @@
 
 namespace WebCore {
 
-class SpeechSynthesisUtterance : public PlatformSpeechSynthesisUtteranceClient, public ScriptWrappable, public RefCounted<SpeechSynthesisUtterance>, public ContextLifecycleObserver, public EventTarget {
+class SpeechSynthesisUtterance : public EventTarget, public PlatformSpeechSynthesisUtteranceClient, public ScriptWrappable, public RefCounted<SpeechSynthesisUtterance>, public ContextLifecycleObserver {
 public:
     static PassRefPtr<SpeechSynthesisUtterance> create(ScriptExecutionContext*, const String&);