Remove useless override of executionContext() in HTMLMediaElement

Source/core/html/HTMLMediaElement.h

Index: Source/core/html/HTMLMediaElement.h
diff --git a/Source/core/html/HTMLMediaElement.h b/Source/core/html/HTMLMediaElement.h
index 4bf6af4bbeea39f58dfe218cdb20ce61a2db06a3..3bda86b84467989e361bb0f08f00516d1c77b77c 100644
--- a/Source/core/html/HTMLMediaElement.h
+++ b/Source/core/html/HTMLMediaElement.h
@@ -235,7 +235,7 @@ public:
     // causes an ambiguity error at compile time. This class's constructor
     // ensures that both implementations return document, so return the result
     // of one of them here.
-    virtual ExecutionContext* executionContext() const OVERRIDE FINAL { return HTMLElement::executionContext(); }
+    using HTMLElement::executionContext;
 
     bool hasSingleSecurityOrigin() const { return !m_player || m_player->hasSingleSecurityOrigin(); }