Update XMLHttpRequest use counter to count workers
Update XMLHttpRequest use counter to count workers

Move UseCounter to createRequest() and use executionContext
instead of document to count XHR sync requests from workers once
http://code.google.com/p/chromium/issues/detail?id=376039 is fixed.

Review URL: https://codereview.chromium.org/342703002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@176448 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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