Don't allow text selection to start on a 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 97b51ca20dc524b43784c32ed43eb0f808276c95..88a71008ffd3a6c8d38d9d015cb0e40cac6cabd7 100644
--- a/Source/core/html/HTMLMediaElement.h
+++ b/Source/core/html/HTMLMediaElement.h
@@ -343,6 +343,8 @@ private:
     virtual void removedFrom(ContainerNode*) override final;
     virtual void didRecalcStyle(StyleRecalcChange) override final;
 
+    virtual bool canStartSelection() const override { return false; }
+
     virtual void didBecomeFullscreenElement() override final;
     virtual void willStopBeingFullscreenElement() override final;
     virtual bool isInteractiveContent() const override final;