Structured cloning: improve DataCloneError reporting.

LayoutTests/fast/dom/Window/script-tests/postmessage-test.js

 if (window.testRunner) {
     testRunner.dumpAsText();
     testRunner.waitUntilDone();
 }
 
 var console = document.getElementById("console");
 
 var messages = [];
 var evalThunks = [];
 
@@ skipping 135 matching lines @@
 window.addEventListener('message', onmessage, false);
 
 function ConstructorWithPrototype(s) {
     this.field = s;
 }
 
 ConstructorWithPrototype.prototype = {
     protoProperty: 2010
 };
 
-window.tryPostMessage = function(message, shouldThrow, expected, expectedExceptionOrEvalThunk) {
+window.tryPostMessage = function(message, shouldThrow, expected, expectedExceptionOrEvalThunk, transferables) {
     if (expected == "evalThunk") {
       var evalThunk = expectedExceptionOrEvalThunk;
     } else {
       var expectedException = expectedExceptionOrEvalThunk;
     }
     try {
         var value = eval(message);
-        postMessage(value, "*");
+        postMessage(value, "*", transferables);
         if (shouldThrow)
             console.innerHTML += "FAIL: 'postMessage("+message+")' should throw but didn't<br>";
         messages.push(expected || message);
         if (expected == "evalThunk") {
             evalThunks.push(evalThunk);
         }
     } catch(e) {
         if (shouldThrow) {
             if (expectedException === undefined || expectedException == e.code || expectedException == e) {
                 console.innerHTML += "PASS: 'postMessage("+message+")' threw " + e + "<br>";
             } else {
                 console.innerHTML += "FAIL: 'postMessage("+message+")' threw " + e + ", was expecting " + expectedException + "<br>";
             }
         } else
             console.innerHTML += "FAIL: 'postMessage("+message+")' should not throw but threw " + e + "<br>";
     }
 }