Don't create layout objects for children of display-none iframes.

third_party/WebKit/Source/core/dom/StyleChangeReason.h

 // Copyright 2014 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.
 
 #ifndef StyleChangeReason_h
 #define StyleChangeReason_h
 
 #include "core/dom/QualifiedName.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class QualifiedName;
 
 namespace StyleChangeReason {
 extern const char ActiveStylesheetsUpdate[];
 extern const char Animation[];
 extern const char Attribute[];
 extern const char CleanupPlaceholderStyles[];
 extern const char CompositorProxy[];
 extern const char ControlValue[];
 extern const char Control[];
 extern const char DeclarativeContent[];
 extern const char DesignMode[];
 extern const char FontSizeChange[];
 extern const char Fonts[];
 extern const char FullScreen[];
+extern const char IFrameDisplayChanged[];
 extern const char Inline[];
 extern const char InlineCSSStyleMutated[];
 extern const char Inspector[];
 extern const char Language[];
 extern const char LinkColorChange[];
 extern const char PlatformColorChange[];
 extern const char PropagateInheritChangeToDistributedNodes[];
 extern const char PropertyRegistration[];
 extern const char PropertyUnregistration[];
 extern const char PseudoClass[];
@@ skipping 61 matching lines @@
   void operator==(const StyleChangeReasonForTracing&) const {}
   void operator!=(const StyleChangeReasonForTracing&) const {}
 
   const char* m_reason;
   AtomicString m_extraData;
 };
 
 }  // namespace blink
 
 #endif  // StyleChangeReason_h