Add Origin Trials Test interface, rather than attaching trials directly to internals.

third_party/WebKit/LayoutTests/http/tests/origin_trials/resources/disabled-worker.js

Index: third_party/WebKit/LayoutTests/http/tests/origin_trials/resources/disabled-worker.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/origin_trials/resources/disabled-worker.js b/third_party/WebKit/LayoutTests/http/tests/origin_trials/resources/disabled-worker.js
index 57619855df62677cd5a023f5d60cc0175026494c..f394750b2578b5969592826f6a9a62feafa74418 100644
--- a/third_party/WebKit/LayoutTests/http/tests/origin_trials/resources/disabled-worker.js
+++ b/third_party/WebKit/LayoutTests/http/tests/origin_trials/resources/disabled-worker.js
@@ -2,11 +2,19 @@ importScripts('/resources/testharness.js');
 
 // The trial should not be enabled.
 test(() => {
-    assert_not_exists(self.internals, 'frobulate');
-    assert_equals(self.internals.frobulate, undefined);
+    var testObject = self.internals.originTrialsTest();
+    assert_idl_attribute(testObject, 'throwingAttribute');
+    assert_throws("NotSupportedError", () => { testObject.throwingAttribute; },
+       'Accessing attribute should throw error');
+  }, 'Accessing attribute should throw error');
+test(() => {
+    var testObject = self.internals.originTrialsTest();
+    assert_not_exists(testObject, 'normalAttribute');
+    assert_equals(testObject.normalAttribute, undefined);
   }, 'Attribute should not exist in worker');
 test(() => {
-    assert_not_exists(self.internals, 'FROBULATE_CONST');
-    assert_equals(self.internals.FROBULATE_CONST, undefined);
+    var testObject = self.internals.originTrialsTest();
+    assert_not_exists(testObject, 'CONSTANT');
+    assert_equals(testObject.CONSTANT, undefined);
   }, 'Constant should not exist in worker');
 done();