Web Inspector: display the number of dirty render objects in Layout timeline event
https://bugs.webkit.org/show_bug.cgi?id=95331

Reviewed by Pavel Feldman.

Source/WebCore:

Count the render objects that need layout in InspectorTimelineAgent::willLayout()
and display the number in popover over Layout record in Timeline panel.

* English.lproj/localizedStrings.js:
* inspector/InspectorTimelineAgent.cpp:
(WebCore::InspectorTimelineAgent::willLayout):
(WebCore::InspectorTimelineAgent::didLayout):
* inspector/TimelineRecordFactory.cpp:
(WebCore):
(WebCore::TimelineRecordFactory::createLayoutData):
(WebCore::TimelineRecordFactory::appendLayoutRoot):
* inspector/TimelineRecordFactory.h:
(TimelineRecordFactory):
* inspector/front-end/TimelinePresentationModel.js:
(WebInspector.TimelinePresentationModel.Record.prototype._generatePopupContentWithImagePreview):

LayoutTests:

* inspector/timeline/timeline-layout-expected.txt: rebaselined to include new properties;

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147422 268f45cc-cd09-0410-ab3c-d52691b4dbfc