HTMLMediaElement::createMediaControls should use AttachLazily

The media element UI controls should be attached lazily.

TBR=eseidel

Review URL: https://chromiumcodereview.appspot.com/23224011

git-svn-id: svn://svn.chromium.org/blink/trunk@156349 bbb929c8-8fbe-4397-9dbb-9b2b20218538
diff --git a/Source/core/html/HTMLMediaElement.cpp b/Source/core/html/HTMLMediaElement.cpp
index a4c6dd0..a7248da 100644
--- a/Source/core/html/HTMLMediaElement.cpp
+++ b/Source/core/html/HTMLMediaElement.cpp
@@ -3688,7 +3688,7 @@
     if (isFullscreen())
         mediaControls->enteredFullscreen();
 
-    ensureUserAgentShadowRoot()->appendChild(mediaControls, ASSERT_NO_EXCEPTION);
+    ensureUserAgentShadowRoot()->appendChild(mediaControls, ASSERT_NO_EXCEPTION, AttachLazily);
 
     if (!controls() || !inDocument())
         mediaControls->hide();