Update geofencing layout tests to use mock service.

LayoutTests/http/tests/geofencing/resources/worker-service-not-available.js

+importScripts('../../serviceworker/resources/worker-testharness.js');
+importScripts('../../resources/testharness-helpers.js');
+
+promise_test(function(test) {
+    return assert_promise_rejects(
+      navigator.geofencing.registerRegion(
+        new CircularGeofencingRegion({latitude: 37.421999,
+                                     longitude: -122.084015})),
+      'AbortError',
+      'registerRegion should fail with an AbortError');
+  }, 'registerRegion should fail');
+
+promise_test(function(test) {
+    return assert_promise_rejects(
+      navigator.geofencing.unregisterRegion(""),
+      'AbortError',
+      'unregisterRegion should fail with an AbortError');
+  }, 'unregisterRegion should fail');
+
+promise_test(function(test) {
+    return assert_promise_rejects(
+      navigator.geofencing.getRegisteredRegions(),
+      'AbortError',
+      'getRegisteredRegions should fail with an AbortError');
+  }, 'getRegisteredRegions should fail');