Implement DataCue interface.

LayoutTests/media/video-test.js

Index: LayoutTests/media/video-test.js
diff --git a/LayoutTests/media/video-test.js b/LayoutTests/media/video-test.js
index e558c1db9a90094ddbfc71a27856c090e750edfb..8c7888869f8011431a39949155bf25f5f2800208 100644
--- a/LayoutTests/media/video-test.js
+++ b/LayoutTests/media/video-test.js
@@ -88,6 +88,7 @@ function testExpected(testFuncString, expected, comparison)
         case '!=':  success = observed != expected; break;
         case '==': success = observed == expected; break;
         case '===': success = observed === expected; break;
+        case 'instanceof': success = observed instanceof expected; break;
     }
 
     reportExpected(success, testFuncString, comparison, expected, observed)
@@ -216,7 +217,7 @@ function testDOMException(testString, exceptionString)
         var exception = ex;
     }
     logResult(exception instanceof DOMException && exception.code === eval(exceptionString),
-        "TEST(" + testString + ") THROWS(" + exceptionString + ": " + exception.message + ")");
+        "TEST(" + testString + ") THROWS(" + exceptionString + ": " + (exception ? exception.message : undefined) + ")");
 }
 
 function testException(testString, exceptionString) {
@@ -229,6 +230,16 @@ function testException(testString, exceptionString) {
         "TEST(" + testString + ") THROWS(" + exceptionString + ")");
 }
 
+function testExceptionType(testString, exceptionTypeString) {
+    try {
+        eval(testString);
+    } catch (ex) {
+        var exception = ex;
+    }
+    logResult(exception instanceof eval(exceptionTypeString),
+        "TEST(" + testString + ") THROWS(" + exceptionTypeString + ")");
+}
+
 var testEnded = false;
 
 function endTest()