buildbot: Use multiple shards on Win Random Order bot.

testing/buildbot/chromium.fyi.json

 {
   "Android Asan Builder Tests (dbg)": {
     "gtest_tests": [
       {
         "args": [
           "--tool=asan"
         ],
         "swarming": {
           "can_use_on_swarming_builders": false
         },
@@ skipping 12920 matching lines @@
           ],
           "shards": 1
         }
       }
     ]
   },
   "WebKit Win - RandomOrder": {
     "isolated_scripts": [
       {
         "isolate_name": "webkit_layout_tests_exparchive",
+        "merge": {
+          "args": [
+            "--verbose",
+            "--results-json-override-with-build-property",
+            "build_number",
+            "buildnumber",
+            "--results-json-override-with-build-property",
+            "builder_name",
+            "buildername",
+            "--results-json-override-with-build-property",
+            "chromium_revision",
+            "got_revision_cp"
+          ],
+          "script": "//third_party/WebKit/Tools/Scripts/merge-layout-test-results"
+        },
         "name": "webkit_layout_tests",
         "swarming": {
           "can_use_on_swarming_builders": true,
           "dimension_sets": [
             {
               "os": "Windows-10-10586"
             },
             {
               "os": "Windows-7-SP1"
             }
           ],
-          "shards": 1
+          "hard_timeout": 900,
+          "shards": 10
         }
       }
     ]
   },
   "Win 10 Fast Ring": {
     "gtest_tests": [
       {
         "swarming": {
           "can_use_on_swarming_builders": false
         },
@@ skipping 224 matching lines @@
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": false
         },
         "test": "views_unittests"
       }
     ]
   }
 }