Web Inspector: Resource content is not loaded if Resource.requestContent method is...

Web Inspector: Resource content is not loaded if Resource.requestContent method is called before network request is finished.
https://bugs.webkit.org/show_bug.cgi?id=90153

Reviewed by Yury Semikhatsky.

Source/WebCore:

Test: http/tests/inspector/resource-tree/resource-request-content-while-loading.html

* inspector/front-end/NetworkRequest.js:
* inspector/front-end/Resource.js:
(WebInspector.Resource):
(WebInspector.Resource.prototype.requestContent):
(WebInspector.Resource.prototype._requestFinished):

LayoutTests:

Resource.requestContent() now checks that request (if there is one) was already loaded before requesting content from PageAgent.
Drive-by: Removed unneeded legacy request._resource field.
* http/tests/inspector/network/network-request-revision-content.html:
* http/tests/inspector/resource-tree/resource-request-content-while-loading-expected.txt: Added.
* http/tests/inspector/resource-tree/resource-request-content-while-loading.html: Added.
* http/tests/inspector/resources-test.js:
(initialize_ResourceTest.InspectorTest.runAfterResourcesAreFinished.checkResources):
(initialize_ResourceTest.InspectorTest.runAfterResourcesAreFinished):
(initialize_ResourceTest.InspectorTest.showResource.showResourceCallback):
(initialize_ResourceTest.InspectorTest.showResource):
(initialize_ResourceTest.InspectorTest.resourceMatchingURL.visit):
(initialize_ResourceTest.InspectorTest.resourceMatchingURL):
(initialize_ResourceTest):
* inspector/debugger/raw-source-code.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121537 268f45cc-cd09-0410-ab3c-d52691b4dbfc