Make w3cwrapper.js's done() match the semantics in testharness.js

This should fix any tests where done() can be called multiple times.

BUG=333880

Review URL: https://codereview.chromium.org/205893003

git-svn-id: svn://svn.chromium.org/blink/trunk@169720 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/media/W3C/w3cwrapper.js

@@ -7,7 +7,7 @@ function getAudioURI(dummy) {
   return "../../../content/test.wav";
 }
 
-function testStep(testFunction){
+function testStep(testFunction) {
   try {
     testFunction();
   } catch (e) {
@@ -15,6 +15,15 @@ function testStep(testFunction){
   }
 }
 
+function testDone() {
+  // Match the semantics of testharness.js done(), where nothing that
+  // happens after that call has any effect on the test result.
+  if (!window.wasFinishJSTestCalled) {
+    finishJSTest();
+    assert_equals = assert_true = assert_false = function() { };
+  }
+}
+
 function test(testFunction) {
   description(document.title);
   testStep(testFunction);
@@ -25,7 +34,7 @@ function async_test(title, options) {
   description(title);
   return {
     step: testStep,
-    done: finishJSTest
+    done: testDone
   }
 }