Fix test configs for tryserver.blink mac10.12, win builders.

This last set of tweaks fixes the swarming configs for a couple
of builders. It looks like things should be back to working now.

TBR=hinoka@chromium.org
NOTRY=true
BUG=853040

Change-Id: Id485754a30a8a22cef5e39e5ea601c78e23cd7d8
Reviewed-on: https://chromium-review.googlesource.com/1103781Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567912}

testing/buildbot/chromium.fyi.json

@@ -7900,7 +7900,32 @@
       }
     ]
   },
-  "mac10.12-blink-rel-dummy": {},
+  "mac10.12-blink-rel-dummy": {
+    "isolated_scripts": [
+      {
+        "isolate_name": "webkit_layout_tests_exparchive",
+        "merge": {
+          "args": [
+            "--verbose"
+          ],
+          "script": "//third_party/blink/tools/merge_web_test_results.py"
+        },
+        "name": "webkit_layout_tests",
+        "only_retry_failed_tests": true,
+        "results_handler": "layout tests",
+        "swarming": {
+          "can_use_on_swarming_builders": true,
+          "dimension_sets": [
+            {
+              "gpu": "none",
+              "os": "Mac-10.12.6"
+            }
+          ],
+          "shards": 12
+        }
+      }
+    ]
+  },
   "mac10.12_retina-blink-rel-dummy": {
     "isolated_scripts": [
       {
@@ -7950,7 +7975,8 @@
               "os": "Mac-10.13"
             }
           ],
-          "hard_timeout": 900
+          "hard_timeout": 900,
+          "shards": 12
         }
       }
     ]
@@ -7978,6 +8004,12 @@
         "results_handler": "layout tests",
         "swarming": {
           "can_use_on_swarming_builders": true,
+          "dimension_sets": [
+            {
+              "os": "Windows-10-15063"
+            }
+          ],
+          "hard_timeout": 900,
           "shards": 12
         }
       }
@@ -7998,6 +8030,12 @@
         "results_handler": "layout tests",
         "swarming": {
           "can_use_on_swarming_builders": true,
+          "dimension_sets": [
+            {
+              "os": "Windows-7-SP1"
+            }
+          ],
+          "hard_timeout": 900,
           "shards": 12
         }
       }

testing/buildbot/waterfalls.pyl

@@ -2111,8 +2111,17 @@
         },
       },
       'mac10.12-blink-rel-dummy': {
-        # TODO(dpranke): Looks like we don't actually run the layout
-        # tests on mac10.12_blink_rel at the moment. We should fix that.
+        'test_suites': {
+          'isolated_scripts': 'chromium_webkit_isolated_scripts',
+        },
+        'swarming': {
+          'dimension_sets': [
+            {
+              'gpu': 'none',
+              'os': 'Mac-10.12.6',
+            }
+          ],
+        },
       },
       'mac10.12_retina-blink-rel-dummy': {
         'test_suites': {
@@ -2142,15 +2151,31 @@
           'hard_timeout': 900,
         },
         'test_suites': {
-          'isolated_scripts': 'webkit_layout_tests_isolated_scripts',
+          'isolated_scripts': 'chromium_webkit_isolated_scripts',
         },
       },
       'win10-blink-rel-dummy': {
+        'swarming': {
+          'dimension_sets': [
+            {
+              'os': 'Windows-10-15063',
+            },
+          ],
+          'hard_timeout': 900,
+        },
         'test_suites': {
           'isolated_scripts': 'chromium_webkit_isolated_scripts',
         },
       },
       'win7-blink-rel-dummy': {
+        'swarming': {
+          'dimension_sets': [
+            {
+              'os': 'Windows-7-SP1',
+            },
+          ],
+          'hard_timeout': 900,
+        },
         'test_suites': {
           'isolated_scripts': 'chromium_webkit_isolated_scripts',
         },