Add JS to git cl format.

This CL adds .js to the list of file extensions that get clang-formatted.

BUG=567770

Change-Id: Ieed162a84ca68877e5107da1824b1f49c71d51ed
Reviewed-on: https://chromium-review.googlesource.com/429551Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Dan Beam <dbeam@chromium.org>

git_cl.py

@@ -5177,7 +5177,7 @@ def MatchingFileType(file_name, extensions):
 @subcommand.usage('[files or directories to diff]')
 def CMDformat(parser, args):
   """Runs auto-formatting tools (clang-format etc.) on the diff."""
-  CLANG_EXTS = ['.cc', '.cpp', '.h', '.m', '.mm', '.proto', '.java']
+  CLANG_EXTS = ['.cc', '.cpp', '.h', '.m', '.mm', '.proto', '.java', '.js']
   GN_EXTS = ['.gn', '.gni', '.typemap']
   parser.add_option('--full', action='store_true',
                     help='Reformat the full content of all touched files')