an assertion failure in Document::updateStyleIfNeeded().

Source/WebCore: 

* dom/NamedFlowCollection.cpp:
(WebCore::NamedFlowCollection::ensureFlowWithName):
(WebCore::NamedFlowCollection::discardNamedFlow):
* inspector/Inspector.json:
* inspector/InspectorCSSAgent.cpp:
(WebCore::InspectorCSSAgent::didCreateNamedFlow):
(WebCore::InspectorCSSAgent::didRemoveNamedFlow):
(WebCore::InspectorCSSAgent::getNamedFlowCollection):
(WebCore::InspectorCSSAgent::getFlowByName):
(WebCore):
* inspector/InspectorCSSAgent.h:
(InspectorCSSAgent):
* inspector/InspectorInstrumentation.cpp:
(WebCore):
(WebCore::InspectorInstrumentation::didCreateNamedFlowImpl):
(WebCore::InspectorInstrumentation::didRemoveNamedFlowImpl):
* inspector/InspectorInstrumentation.h:
(InspectorInstrumentation):
(WebCore::InspectorInstrumentation::didCreateNamedFlow):
(WebCore::InspectorInstrumentation::didRemoveNamedFlow):
* inspector/front-end/CSSStyleModel.js:
(WebInspector.CSSStyleModel):
(WebInspector.CSSStyleModel.prototype.getNamedFlowCollectionAsync):
(WebInspector.CSSStyleModel.prototype.getFlowByNameAsync):
(WebInspector.CSSStyleModel.prototype._namedFlowCreated.callback):
(WebInspector.CSSStyleModel.prototype._namedFlowCreated):
(WebInspector.CSSStyleModel.prototype._namedFlowRemoved.callback):
(WebInspector.CSSStyleModel.prototype._namedFlowRemoved):
(WebInspector.CSSDispatcher.prototype.namedFlowCreated):
(WebInspector.CSSDispatcher.prototype.namedFlowRemoved):
(WebInspector.NamedFlow):
(WebInspector.NamedFlow.parsePayloadArray):
* rendering/RenderNamedFlowThread.cpp:
(WebCore::RenderNamedFlowThread::dispatchRegionLayoutUpdateEvent):

LayoutTests: 

* inspector/styles/protocol-css-regions-commands-expected.txt:
* inspector/styles/protocol-css-regions-commands.html:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@127500 268f45cc-cd09-0410-ab3c-d52691b4dbfc