Add experimental Support for DOM3 KeyboardEvent key value

Source/core/events/KeyboardEvent.h

Index: Source/core/events/KeyboardEvent.h
diff --git a/Source/core/events/KeyboardEvent.h b/Source/core/events/KeyboardEvent.h
index 2f7101663278802f61b88f14800e5dc1f6932672..95794dd86ec9236785f0fabe42b753d85dcbac1d 100644
--- a/Source/core/events/KeyboardEvent.h
+++ b/Source/core/events/KeyboardEvent.h
@@ -59,10 +59,10 @@ public:
     }
 
     static PassRefPtrWillBeRawPtr<KeyboardEvent> create(const AtomicString& type, bool canBubble, bool cancelable, AbstractView* view,
-        const String& keyIdentifier, const String& code, unsigned location,
+        const String& keyIdentifier, const String& code, const String& key, unsigned location,
         bool ctrlKey, bool altKey, bool shiftKey, bool metaKey)
     {
-        return adoptRefWillBeNoop(new KeyboardEvent(type, canBubble, cancelable, view, keyIdentifier, code, location,
+        return adoptRefWillBeNoop(new KeyboardEvent(type, canBubble, cancelable, view, keyIdentifier, code, key, location,
         ctrlKey, altKey, shiftKey, metaKey));
     }
 
@@ -74,6 +74,7 @@ public:
 
     const String& keyIdentifier() const { return m_keyIdentifier; }
     const String& code() const { return m_code; }
+    const String& key() const { return m_key; }
 
     unsigned location() const { return m_location; }
 
@@ -96,12 +97,13 @@ private:
     KeyboardEvent(const PlatformKeyboardEvent&, AbstractView*);
     KeyboardEvent(const AtomicString&, const KeyboardEventInit&);
     KeyboardEvent(const AtomicString& type, bool canBubble, bool cancelable, AbstractView*,
-        const String& keyIdentifier, const String& code, unsigned location,
+        const String& keyIdentifier, const String& code, const String& key, unsigned location,
         bool ctrlKey, bool altKey, bool shiftKey, bool metaKey);
 
     OwnPtr<PlatformKeyboardEvent> m_keyEvent;
     String m_keyIdentifier;
     String m_code;
+    String m_key;
     unsigned m_location;
     bool m_isAutoRepeat : 1;
 };