Stop logging the start of a run for individual layout tests.

NOTRY=true
NOPRESUBMIT=true
NOTREECHECKS=true
BUG=673207

Review-Url: https://codereview.chromium.org/2564343003
Cr-Commit-Position: refs/heads/master@{#437924}

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/controllers/layout_test_runner.py

@@ -286,7 +286,7 @@ class Worker(object):
         self._update_test_input(test_input)
         start = time.time()
 
-        _log.debug("%s %s started", self._name, test_input.test_name)
+        # TODO(qyearsley): Re-add logging if it doesn't create too much load (crbug.com/673207).
         self._caller.post('started_test', test_input)
         result = single_test_runner.run_single_test(
             self._port, self._options, self._results_directory, self._name,