Do not require DevTools extension resources to be white-listed in manifest.

Currently, resources used by DevTools extensions need to be white-listed as web_accessible_resources in manifest. This is quite inconvenitent and appears to be an overkill, given the fact that DevTools front-end is
 (a) trusted and
 (b) picky on the frames it loads.
This change adds resources that belong to DevTools extensions and are being loaded into a DevTools front-end page to the list of exceptions from web_accessible_resources check.

BUG=none
TEST=DevToolsExtensionTest.*

Review URL: https://chromiumcodereview.appspot.com/9663076

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@126378 0039d316-1c4b-4281-b951-d872f2087c98
void ChromeContentRendererClient::WillReleaseScriptContext(
    WebFrame* frame, v8::Handle<v8::Context> context, int world_id) {
  extension_dispatcher_->WillReleaseScriptContext(frame, context, world_id);
}

void ChromeContentRendererClient::WillReleaseScriptContext(
    WebFrame* frame, v8::Handle<v8::Context> context, int world_id) {
  extension_dispatcher_->WillReleaseScriptContext(frame, context, world_id);
}
