[Reland #1] 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 7f4022656d7f19297e6514977aa703154962a14b..0aacd064e78351eea7967bcd17df70163de65410 100644
--- a/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
@@ -90,6 +90,7 @@ class CORE_EXPORT HTMLFrameOwnerElement : public HTMLElement,
   int marginHeight() const override { return -1; }
   bool allowFullscreen() const override { return false; }
   bool allowPaymentRequest() const override { return false; }
+  bool isDisplayNone() const override { return !m_widget; }
   AtomicString csp() const override { return nullAtom; }
   const WebVector<mojom::blink::PermissionName>& delegatedPermissions()
       const override;
@@ -107,6 +108,7 @@ class CORE_EXPORT HTMLFrameOwnerElement : public HTMLElement,
   bool isKeyboardFocusable() const override;
 
   void disposeWidgetSoon(FrameViewBase*);
+  void frameOwnerPropertiesChanged();
 
  private:
   // Intentionally private to prevent redundant checks when the type is