[webcrypto] Make KeyPair structured clonable.

LayoutTests/crypto/resources/common.js

 function logError(error)
 {
     debug("error is: " + error.toString());
 }
 
 // Verifies that the given "bytes" holds the same value as "expectedHexString".
 // "bytes" can be anything recognized by "bytesToHexString()".
 function bytesShouldMatchHexString(testDescription, expectedHexString, bytes)
 {
     expectedHexString = "[" + expectedHexString.toLowerCase() + "]";
@@ skipping 51 matching lines @@
         chars.push(str.charCodeAt(i));
     return new Uint8Array(chars);
 }
 
 function failAndFinishJSTest(error)
 {
     testFailed('' + error);
     finishJSTest();
 }
 
-// Returns a Promise for the cloned key.
+// FIXME: Delete this and use cloneObject() directly.
 function cloneKey(key)
 {
+    return cloneObject(key);
+}
+
+// Returns a Promise for the cloned object.
+function cloneObject(obj)
+{
     // Sending an object through a MessagePort implicitly clones it.
     // Use a single MessageChannel so requests complete in FIFO order.
-    var self = cloneKey;
+    var self = cloneObject;
     if (!self.channel) {
         self.channel = new MessageChannel();
         self.callbacks = [];
         self.channel.port1.addEventListener('message', function(e) {
             var callback = self.callbacks.shift();
             callback(e.data);
         }, false);
         self.channel.port1.start();
     }
 
     return new Promise(function(resolve, reject) {
         self.callbacks.push(resolve);
-        self.channel.port2.postMessage(key);
+        self.channel.port2.postMessage(obj);
     });
 }
 
 // Logging the serialized format ensures that if it changes it will break tests.
 function logSerializedKey(o)
 {
     if (internals) {
         // Removing the version tag from the output so serialization format changes don't need to update all the crypto tests.
         var serialized = internals.serializeObject(o);
         var serializedWithoutVersion = new Uint8Array(serialized, 2);
         debug("Serialized key bytes: " + bytesToHexString(serializedWithoutVersion));
     }
 }
 
 function shouldEvaluateAs(actual, expectedValue)
 {
     if (typeof expectedValue == "string")
         return shouldBeEqualToString(actual, expectedValue);
     return shouldEvaluateTo(actual, expectedValue);
 }