DevTools: Remove unneeded didReceiveXHRResponse instrumentation.

This method was used to detect the type of synchronous XHR requests.
Now that synchronous XHRs use RawResource for loading it is no longer needed.

R=pfeldman, caseq

Review URL: https://codereview.chromium.org/106663005

git-svn-id: svn://svn.chromium.org/blink/trunk@163554 bbb929c8-8fbe-4397-9dbb-9b2b20218538