Revert "Stop running webkit_layout_tests on mac 10.12 and 10.13 w/ GPUs."

This reverts commit e64c72b93c42763e3adc6ff37568737400bb33f2.

Reason for revert: This causes the https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Mac10.12%20Tests bot to turn red with webkit_layout_tests failures that are empty.

Original change's description:
> Stop running webkit_layout_tests on mac 10.12 and 10.13 w/ GPUs.
>
> And disable http/tests/media/video-load-metadata-decode-error.html,
> which appears to have a dependency on GPUs.
>
> Bug: 854874, 871445
> Change-Id: I254ce21953ac428351203d6479e1936347ce5b4c
> Reviewed-on: https://chromium-review.googlesource.com/1162963
> Commit-Queue: Ben Pastene <[email protected]>
> Reviewed-by: Kenneth Russell <[email protected]>
> Reviewed-by: Dirk Pranke <[email protected]>
> Cr-Commit-Position: refs/heads/master@{#581074}

[email protected],[email protected],[email protected]

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 854874, 871445, 871830
Change-Id: Ia9963a9f3cb6dbaad0f7a8b78723bf0dc034d052
Reviewed-on: https://chromium-review.googlesource.com/1165846
Commit-Queue: Ben Pastene <[email protected]>
Reviewed-by: Ben Pastene <[email protected]>
Cr-Commit-Position: refs/heads/master@{#581297}
diff --git a/testing/buildbot/test_suite_exceptions.pyl b/testing/buildbot/test_suite_exceptions.pyl
index 0c714e45..0873543 100644
--- a/testing/buildbot/test_suite_exceptions.pyl
+++ b/testing/buildbot/test_suite_exceptions.pyl
@@ -1644,7 +1644,7 @@
         'swarming': {
           'dimension_sets': [
             {
-              'gpu': 'none',
+              'gpu': '8086:0a2e',
               'os': 'Mac-10.12.6',
             },
           ],
@@ -1655,7 +1655,7 @@
         # TODO(crbug.com/853356): Switch this to 10.13.
         'use_multi_dimension_trigger_script': True,
         'alternate_swarming_dimensions': [{
-          'gpu': 'none',
+          'gpu': '8086:0a2e',
           'os': 'Mac-10.12.6',
         }],
 
@@ -1664,7 +1664,7 @@
         'swarming': {
           'dimension_sets': [
             {
-              'gpu': 'none',
+              'gpu': '8086:0a2e',
               'os': 'Mac-10.13',
             },
           ],