Run accessibility_unittests on mac asan.

They seem to pass.

Bug: 843511
Change-Id: I7e52d8cc7301d4d3bc87e03242124ce1b22c0000
Reviewed-on: https://chromium-review.googlesource.com/1104797
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568047}

testing/buildbot/chromium.memory.json

@@ -6073,6 +6073,12 @@
   },
   "Mac ASan 64 Tests (1)": {
     "gtest_tests": [
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "accessibility_unittests"
+      },
       {
         "swarming": {
           "can_use_on_swarming_builders": true

testing/buildbot/test_suite_exceptions.pyl

@@ -16,11 +16,6 @@
 # The goal is to drive the number of exceptions to zero, to make all
 # the bots behave similarly.
 {
-  'accessibility_unittests': {
-    'remove_from': [
-      'Mac ASan 64 Tests (1)',
-    ],
-  },
   'android_webview_unittests': {
     'remove_from': [
       # On chromium.android, these do not need to run prior to M.