Don't run IntersectionObserver lifecycle in frames with dirty layout.

third_party/WebKit/Source/web/tests/DeferredLoadingTest.cpp

 // Copyright 2016 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/exported/WebViewBase.h"
 #include "platform/testing/HistogramTester.h"
 #include "platform/testing/UnitTestHelpers.h"
 #include "web/WebLocalFrameImpl.h"
 #include "web/tests/sim/SimCompositor.h"
 #include "web/tests/sim/SimDisplayItemList.h"
@@ skipping 285 matching lines @@
       "<iframe id='theFrame' style='position:absolute; top:205vh' sandbox>"
       "</iframe>");
 
   CompositeFrame();
 
   ExpectCount(WouldLoadReason::kCreated, 1);
   ExpectCount(WouldLoadReason::k2ScreensAway, 1);
   ExpectCount(WouldLoadReason::k3ScreensAway, 1);
   ExpectTotalCount(3);
 
   main_resource->Write("<script>theFrame.style.display='none'</script>");

[dgrogan, 2017/05/03 15:46:20]

Deferred frame loading would load the document in all display:none frames. The
test is simulating script making a previously offscreen and unloaded frame
display:none and ensuring that it's counted as having to load.

With the !NeedsLayout() change, display:none frames would only be counted as
must load if there's another change to the DOM, as line 312 below does. It's
probably a very cornery case, a page changing a frame to display:none and then
not touching the DOM anymore, but it is a difference in how we count frames for
loading, so we should bump up the version number of the histogram.

Could you change Navigation.DeferredDocumentLoading.StatesV4 to V5:
 - at the top of this file
 -
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/dom/Docum...
 - and in histograms.xml

In histograms.xml, deprecate V4, add a new V5 with the <summary>
"""Why and if cross-origin documents would be loaded if we were to defer loading
as long as possible. Changes from V4: frames made display:none will only be
counted as must load after a subsequent change to the DOM.
"""

Sorry for the busy work and for punishing a good deed :(

 
   CompositeFrame();
 
-  ExpectTotalCount(6);
+  ExpectTotalCount(3);
 
   main_resource->Write(
       "<script>document.body.appendChild(document.createElement"
       "('iframe'));</script>");
   main_resource->Finish();
 
   CompositeFrame();
 
   ExpectCount(WouldLoadReason::kCreated, 1);
   ExpectCount(WouldLoadReason::kNoParent, 1);
@@ skipping 170 matching lines @@
 
   ExpectCount(WouldLoadReason::kCreated, 1);
   ExpectCount(WouldLoadReason::kVisible, 1);
   ExpectCount(WouldLoadReason::k1ScreenAway, 1);
   ExpectCount(WouldLoadReason::k2ScreensAway, 1);
   ExpectCount(WouldLoadReason::k3ScreensAway, 1);
   ExpectTotalCount(5);
 }
 
 }  // namespace blink