Bug 1540569: Set TZ and LC_ALL for jstestbrowser suite following the jstest shell runner. r=ahal

The shell runner explicitly sets TZ=PST8PDT and LC_ALL=en_US.UTF-8 for the
jstest test suite. Use the same environment defaults when running this test
suite in the browser.

Differential Revision: https://phabricator.services.mozilla.com/D25908

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

js/src/tests/lib/tests.py

@@ -69,6 +69,7 @@ def get_environment_overlay(js_shell):
     Build a dict of additional environment variables that must be set to run
     tests successfully.
     """
+    # When updating this also update |buildBrowserEnv| in layout/tools/reftest/runreftest.py.
     env = {
         # Force Pacific time zone to avoid failures in Date tests.
         'TZ': 'PST8PDT',

layout/tools/reftest/runreftest.py

@@ -437,6 +437,12 @@ class RefTest(object):
             else:
                 browserEnv["ASAN_OPTIONS"] = "detect_leaks=0"
 
+        # Set environment defaults for jstestbrowser. Keep in sync with the
+        # defaults used in js/src/tests/lib/tests.py.
+        if options.suite == "jstestbrowser":
+            browserEnv["TZ"] = "PST8PDT"
+            browserEnv["LC_ALL"] = "en_US.UTF-8"
+
         for v in options.environment:
             ix = v.find("=")
             if ix <= 0: