Bug 1555479 - Update run-task to support bitbar. r=tomprince

Currently all jobs run on bitbar go through mozharness-test. However for
WebRender standalone testing (i.e. built without any Gecko stuff) we want
to run the WebRender wrench test harness on bitbar using run-task. This
adds the necessary support to run-task.

Differential Revision: https://phabricator.services.mozilla.com/D33408

--HG--
extra : moz-landing-system : lando

taskcluster/taskgraph/transforms/job/run_task.py

@@ -131,6 +131,7 @@ def generic_worker_run_task(config, job, taskdesc):
     worker = taskdesc['worker'] = job['worker']
     is_win = worker['os'] == 'windows'
     is_mac = worker['os'] == 'macosx'
+    is_bitbar = worker['os'] == 'linux-bitbar'
 
     if is_win:
         command = ['C:/mozilla-build/python3/python3.exe', 'run-task']
@@ -172,6 +173,10 @@ def generic_worker_run_task(config, job, taskdesc):
     if run['run-as-root']:
         command.extend(('--user', 'root', '--group', 'root'))
     command.append('--')
+    if is_bitbar:
+        # Use the bitbar wrapper script which sets up the device and adb
+        # environment variables
+        command.append('/builds/taskcluster/script.py')
     command.extend(run_command)
 
     if is_win: