[test] Roll out new test runner to mac bots

TBR=sergiyb@chromium.org

Bug: v8:7343
Change-Id: Id2f60f248b40592607a0bf8f74e1169866e317d7
Reviewed-on: https://chromium-review.googlesource.com/880947Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50803}

tools/testrunner/standard_runner.py

@@ -88,10 +88,12 @@ PREDICTABLE_WRAPPER = os.path.join(
 BUILDER_WHITELIST_STAGING = {
   'client.v8': [
     re.compile(r'V8 Linux64.*'),
+    re.compile(r'V8 Mac.*'),
     re.compile(r'V8 Win.*'),
   ],
   'tryserver.v8': [
     re.compile(r'v8_linux64.*'),
+    re.compile(r'v8_mac.*'),
     re.compile(r'v8_win.*'),
   ],
 }