bindings: Do not try to list files in non existing directory

Running bindings_test on local machine without --reset-results
removes all temporary generated cache files.
In the process, we get a list of files to be removed,
but it fails if the target directory does not exist.
This happens when a test fails in some situation.

This CL makes to skip iterating non existing directories.

Bug: None
Change-Id: Ib18dc2bd4ab8fa5d93863e5d29ca97cbd7241384
Reviewed-on: https://chromium-review.googlesource.com/c/1295757Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602204}

third_party/blink/tools/blinkpy/bindings/bindings_tests.py

@@ -197,6 +197,9 @@ def bindings_tests(output_directory, verbose, suppress_diff):
     executive = Executive()
 
     def list_files(directory):
+        if not os.path.isdir(directory):
+            return []
+
         files = []
         for component in os.listdir(directory):
             if component not in COMPONENT_DIRECTORY: