Web Inspector: add "show paint rectangles" setting.

Web Inspector: add "show paint rectangles" setting.
https://bugs.webkit.org/show_bug.cgi?id=79030

Reviewed by Yury Semikhatsky.

* English.lproj/localizedStrings.js:
* inspector/DOMNodeHighlighter.cpp:
(WebCore::DOMNodeHighlighter::drawOutline):
(DOMNodeHighlighter):
* inspector/DOMNodeHighlighter.h:
(WebCore):
(DOMNodeHighlighter):
* inspector/Inspector.json:
* inspector/InspectorController.cpp:
(WebCore::InspectorController::InspectorController):
* inspector/InspectorInstrumentation.cpp:
(WebCore::InspectorInstrumentation::willPaintImpl):
(WebCore::InspectorInstrumentation::didPaintImpl):
* inspector/InspectorInstrumentation.h:
(WebCore):
(InspectorInstrumentation):
(WebCore::InspectorInstrumentation::willPaint):
* inspector/InspectorPageAgent.cpp:
(PageAgentState):
(WebCore::InspectorPageAgent::create):
(WebCore::InspectorPageAgent::InspectorPageAgent):
(WebCore::InspectorPageAgent::setShowPaintRects):
(WebCore):
(WebCore::InspectorPageAgent::didClearWindowObjectInWorld):
(WebCore::InspectorPageAgent::willPaint):
(WebCore::InspectorPageAgent::didPaint):
(WebCore::InspectorPageAgent::buildObjectForFrame):
* inspector/InspectorPageAgent.h:
(WebCore):
* inspector/front-end/Settings.js:
(WebInspector.Settings):
* inspector/front-end/SettingsScreen.js:
(WebInspector.SettingsScreen):
(WebInspector.SettingsScreen.prototype._showPaintRectsChanged):
* inspector/front-end/inspector.js:
* page/FrameView.cpp:
(WebCore::FrameView::paintContents):
* rendering/RenderLayerBacking.cpp:
(WebCore::RenderLayerBacking::paintContents):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108330 268f45cc-cd09-0410-ab3c-d52691b4dbfc