More informative error messages for non-Transferables.

LayoutTests/fast/events/resources/message-port-multi.js

 if (window.testRunner) {
     testRunner.dumpAsText();
     testRunner.waitUntilDone();
 }
 
 description("This test checks the various use cases around sending multiple ports through MessagePort.postMessage");
 
 var channel = new MessageChannel();
 var channel2 = new MessageChannel();
 var channel3 = new MessageChannel();
 var channel4 = new MessageChannel();
 
 channel.port1.postMessage("noport");
 channel.port1.postMessage("zero ports", []);
 channel.port1.postMessage("two ports", [channel2.port1, channel2.port2]);
 
 // Now test various failure cases
 shouldThrow('channel.port1.postMessage("same port", [channel.port1])', '"DataCloneError: Failed to execute \'postMessage\' on \'MessagePort\': Item #0 in the array of ports contains the source port."');
 shouldThrow('channel.port1.postMessage("entangled port", [channel.port2])', '"DataCloneError: Failed to execute \'postMessage\' on \'MessagePort\': Item #0 in the array of ports contains the target port."');
 shouldThrow('channel.port1.postMessage("null port", [channel3.port1, null, channel3.port2])', "'DataCloneError: An object could not be cloned.'");
 shouldThrow('channel.port1.postMessage("notAPort", [channel3.port1, {}, channel3.port2])', "'DataCloneError: An object could not be cloned.'");
 shouldThrow('channel.port1.postMessage("duplicate port", [channel3.port1, channel3.port1])', "'DataCloneError: An object could not be cloned.'");
 // Should be OK to send channel3.port1 (should not have been disentangled by the previous failed calls).
 channel.port1.postMessage("entangled ports", [channel3.port1, channel3.port2]);
 
-shouldThrow('channel.port1.postMessage("notAnArray", channel3.port1)', "'TypeError: Type error'")
+shouldThrow('channel.port1.postMessage("notAnArray", channel3.port1)', '"TypeError: Failed to execute \'postMessage\' on \'MessagePort\': Second argument is neither an array, nor does it have indexed properties."');
 shouldThrow('channel.port1.postMessage("notASequence", [{length: 3}])', "'DataCloneError: An object could not be cloned.'");
 
 // Should not crash (we should figure out that the array contains undefined
 // entries).
 var largePortArray = [];
 largePortArray[1234567890] = channel4.port1;
 shouldThrow('channel.port1.postMessage("largeSequence", largePortArray)', "'DataCloneError: An object could not be cloned.'");
 
 channel.port1.postMessage("done");
 
@@ skipping 45 matching lines @@
         else
           testPassed("Sending Error object should throw a DataCloneError, got: " + e);
     }
     c4.port1.postMessage("Should succeed");
     channel0.port1.postMessage({id:"done"});
 
     channel0.port2.onmessage = function(event) {
         if (event.data.id == "send-port") {
             if (event.ports && event.ports.length > 0 && event.ports[0] === event.data.port)
                 testPassed("send-port: transferred one port");
-            else 
+            else
                 testFailed("send-port: port transfer failed");
         } else if (event.data.id == "send-port-twice") {
-            if (event.ports && event.ports.length == 1 && 
-                  event.ports[0] === event.data.port0 && event.ports[0] === event.data.port1) 
+            if (event.ports && event.ports.length == 1 &&
+                  event.ports[0] === event.data.port0 && event.ports[0] === event.data.port1)
                 testPassed("send-port-twice: transferred one port twice");
             else
                 testFailed("send-port-twice: failed to transfer one port twice");
         } else if (event.data.id == "send-two-ports") {
-            if (event.ports && event.ports.length == 2 && 
-                  event.ports[0] === event.data.port0 && event.ports[1] === event.data.port1) 
+            if (event.ports && event.ports.length == 2 &&
+                  event.ports[0] === event.data.port0 && event.ports[1] === event.data.port1)
                 testPassed("send-two-ports: transferred two ports");
             else
                 testFailed("send-two-ports: failed to transfer two ports");
         } else if (event.data.id == "done") {
             debug('<br><span class="pass">TEST COMPLETE</span>');
             if (window.testRunner)
             testRunner.notifyDone();
         } else {
             testFailed("Unexpected message " + event.data);
         }
@@ skipping 25 matching lines @@
         if (event.ports.length == 2)
             testPassed("event.ports contains two ports when two ports re-sent after error");
         else
             testFailed("event.ports contained " + event.ports.length + " when two ports re-sent after error");
     } else if (event.data == "done") {
         testTransfers();
     } else
         testFailed("Received unexpected message: " + event.data);
 }