Fix roll_webgl_conformance.py

Bug: None
Change-Id: I91ead42f4a6bc96d55ef369da9c9770d9de4f515
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1941687
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719984}

tools/roll_webgl_conformance.py

@@ -320,7 +320,7 @@ class AutoRoller(object):
     dep_revision = '%s@%s' % (dep_name, commit_info.git_commit)
     self._RunCommand(
         ['gclient', 'setdep', '-r', dep_revision],
-        cwd=os.path.dirname(deps_filename))
+        working_dir=os.path.dirname(deps_filename))
 
   def _UpdateWebGLRevTextFile(self, txt_filename, commit_info):
     # Rolling the WebGL conformance tests must cause at least all of