More informative error messages for non-Transferables.

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

Index: LayoutTests/fast/events/resources/message-port-multi.js
diff --git a/LayoutTests/fast/events/resources/message-port-multi.js b/LayoutTests/fast/events/resources/message-port-multi.js
index b3c0aa330051a6a15e9801fc71dc1f24e5b35f68..ac8304ec0b652374ecc38c79deff8cedb424fad5 100644
--- a/LayoutTests/fast/events/resources/message-port-multi.js
+++ b/LayoutTests/fast/events/resources/message-port-multi.js
@@ -23,7 +23,7 @@ shouldThrow('channel.port1.postMessage("duplicate port", [channel3.port1, channe
 // 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
@@ -89,17 +89,17 @@ function testTransfers() {
         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");