[Reland #1] Don't create layout objects for children of display-none iframes.

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index e184fe385333a69833f7ddf0a12bd685793567e7..ca40e57293351435cc57a2156adcb69b0a4b702c 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -2468,6 +2468,7 @@ void Document::shutdown() {
   // detaching Document is not in a consistent state.
   ScriptForbiddenScope forbidScript;
 
+  m_lifecycle.advanceTo(DocumentLifecycle::Stopping);
   view()->dispose();
 
   // If the FrameViewBase of the document's frame owner doesn't match view()
@@ -2480,8 +2481,6 @@ void Document::shutdown() {
 
   m_markers->prepareForDestruction();
 
-  m_lifecycle.advanceTo(DocumentLifecycle::Stopping);
-
   if (page())
     page()->documentDetached(this);
   probe::documentDetached(this);
@@ -4564,13 +4563,21 @@ HTMLFrameOwnerElement* Document::localOwner() const {
 
 void Document::willChangeFrameOwnerProperties(int marginWidth,
                                               int marginHeight,
-                                              ScrollbarMode scrollingMode) {
-  if (!body())
-    return;
-
+                                              ScrollbarMode scrollingMode,
+                                              bool isDisplayNone) {
   DCHECK(frame() && frame()->owner());
   FrameOwner* owner = frame()->owner();
 
+  if (documentElement()) {
+    if (isDisplayNone != owner->isDisplayNone()) {
+      if (m_lifecycle.state() < DocumentLifecycle::Stopping)

[esprehn, 2017/03/28 21:49:24]

remove this, lazyReattachIfAttached() checks inActiveDocument() which already
checks this for you.

In general explicit checks on the lifecycle are frowned upon, isActive() is
better.

[erikchen, 2017/03/29 20:16:54]

Done.

+        documentElement()->lazyReattachIfAttached();
+    }
+  }
+
+  if (!body())
+    return;
+
   if (marginWidth != owner->marginWidth())
     body()->setIntegralAttribute(marginwidthAttr, marginWidth);
   if (marginHeight != owner->marginHeight())