Eliminate unnecessary includes and pointless forward declarations in LayoutBlock.h

third_party/WebKit/Source/core/html/shadow/MediaControlsTest.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/html/shadow/MediaControls.h"
 
 #include "core/HTMLNames.h"
 #include "core/css/StylePropertySet.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementTraversal.h"
+#include "core/dom/StyleEngine.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLVideoElement.h"
 #include "core/testing/DummyPageHolder.h"
 #include "platform/heap/Handle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
 
 namespace {
 
@@ skipping 165 matching lines @@
     mediaControls().mediaElement().setBooleanAttribute(HTMLNames::disableremoteplaybackAttr, true);
     simulateRouteAvailabe();
     ASSERT_FALSE(isElementVisible(*castOverlayButton));
 
     mediaControls().mediaElement().setBooleanAttribute(HTMLNames::disableremoteplaybackAttr, false);
     mediaControls().reset();
     ASSERT_TRUE(isElementVisible(*castOverlayButton));
 }
 
 } // namespace blink