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

third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h

Index: third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h b/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
index 996939a7fdbdacfbf0ad0535c47cf7a408c330d9..e6f28e66ab84a8aa822dc234ee2d482d34746b09 100644
--- a/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
@@ -86,6 +86,7 @@ class CORE_EXPORT HTMLFrameOwnerElement : public HTMLElement,
   int marginWidth() const override { return -1; }
   int marginHeight() const override { return -1; }
   bool allowFullscreen() const override { return false; }
+  bool isDisplayNone() const override { return !m_widget; }
   AtomicString csp() const override { return nullAtom; }
   const WebVector<WebPermissionType>& delegatedPermissions() const override;
 
@@ -101,6 +102,7 @@ class CORE_EXPORT HTMLFrameOwnerElement : public HTMLElement,
   bool isKeyboardFocusable() const override;
 
   void disposeWidgetSoon(Widget*);
+  void frameOwnerPropertiesChanged();
 
  private:
   // Intentionally private to prevent redundant checks when the type is