Fix web_feature/PRESUBMIT.py broken since r636661

r636661 changed a relative path to update_histogram_enum.py.

Change-Id: I2692e5afafd7590355d58dfaaef69be9968c93c3
Reviewed-on: https://chromium-review.googlesource.com/c/1496266Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636718}

third_party/blink/public/mojom/web_feature/PRESUBMIT.py

@@ -15,7 +15,7 @@ def _RunUmaHistogramChecks(input_api, output_api):  # pylint: disable=C0103
     original_sys_path = sys.path
     try:
         sys.path = sys.path + [input_api.os_path.join(
-            input_api.PresubmitLocalPath(), '..', '..', '..', '..',
+            input_api.PresubmitLocalPath(), '..', '..', '..', '..', '..',
             'tools', 'metrics', 'histograms')]
         import update_histogram_enum  # pylint: disable=F0401
     finally: