Have V8WorkerGlobalScopeEventListener::callListenerFunction() use V8TRYCATCH_FOR_V8STRINGRESOURCE_RETURN()

Have V8WorkerGlobalScopeEventListener::callListenerFunction() use V8TRYCATCH_FOR_V8STRINGRESOURCE_RETURN()
macro instead of toWebCoreString(v8::Handle<v8::Value>) so that we abort the function in case
v8::Value::ToString() threw an exception.

R=haraken

Review URL: https://codereview.chromium.org/61933006

git-svn-id: svn://svn.chromium.org/blink/trunk@162135 bbb929c8-8fbe-4397-9dbb-9b2b20218538