--- a/testing/mozharness/scripts/web_platform_tests.py
+++ b/testing/mozharness/scripts/web_platform_tests.py
@@ -8,16 +8,18 @@ import copy
 import os
 import sys
 
 from datetime import datetime, timedelta
 
 # load modules from parent dir
 sys.path.insert(1, os.path.dirname(sys.path[0]))
 
+import mozinfo
+
 from mozharness.base.errors import BaseErrorList
 from mozharness.base.script import PreScriptAction
 from mozharness.base.vcs.vcsbase import MercurialScript
 from mozharness.mozilla.testing.testbase import TestingMixin, testing_config_options
 from mozharness.mozilla.testing.codecoverage import (
     CodeCoverageMixin,
     code_coverage_config_options
 )
@@ -176,28 +178,30 @@ class WebPlatformTest(TestingMixin, Merc
         cmd = [self.query_python_path('python'), '-u']
         cmd.append(os.path.join(dirs["abs_wpttest_dir"], run_file_name))
 
         # Make sure that the logging directory exists
         if self.mkdir_p(dirs["abs_blob_upload_dir"]) == -1:
             self.fatal("Could not create blobber upload directory")
             # Exit
 
+        mozinfo.find_and_update_from_json(dirs['abs_test_install_dir'])
+
         cmd += ["--log-raw=-",
                 "--log-raw=%s" % os.path.join(dirs["abs_blob_upload_dir"],
                                               "wpt_raw.log"),
                 "--log-wptreport=%s" % os.path.join(dirs["abs_blob_upload_dir"],
                                                     "wptreport.json"),
                 "--log-errorsummary=%s" % os.path.join(dirs["abs_blob_upload_dir"],
                                                        "wpt_errorsummary.log"),
                 "--binary=%s" % self.binary_path,
                 "--symbols-path=%s" % self.query_symbols_url(),
                 "--stackwalk-binary=%s" % self.query_minidump_stackwalk(),
                 "--stackfix-dir=%s" % os.path.join(dirs["abs_test_install_dir"], "bin"),
-                "--run-by-dir=3",
+                "--run-by-dir=%i" % (3 if not mozinfo.info["asan"] else 0),
                 "--no-pause-after-test"]
 
         if not sys.platform.startswith("linux"):
             cmd += ["--exclude=css"]
 
         for test_type in test_types:
             cmd.append("--test-type=%s" % test_type)
 

--- a/testing/web-platform/tests/tools/wptrunner/wptrunner/testloader.py
+++ b/testing/web-platform/tests/tools/wptrunner/wptrunner/testloader.py
@@ -654,17 +654,17 @@ class SingleTestSource(TestSource):
 
         return test_queue
 
 
 class PathGroupedSource(GroupedSource):
     @classmethod
     def new_group(cls, state, test, **kwargs):
         depth = kwargs.get("depth")
-        if depth is True:
+        if depth is True or depth == 0:
             depth = None
         path = urlparse.urlsplit(test.url).path.split("/")[1:-1][:depth]
         rv = path != state.get("prev_path")
         state["prev_path"] = path
         return rv
 
     @classmethod
     def group_metadata(cls, state):