[webcrypto] Update layout tests to match idl generator changes.

LayoutTests/crypto/resources/common.js

+function shouldBeTypeError(toEval)
+{
+    var value = eval(toEval);
+    if (value instanceof TypeError) {
+        testPassed(toEval + " is: " + value.toString());
+    } else {
+        testFailed(toEval + " is not a TypeError: " + value);
+    }
+}
+
 // 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() + "]";
     var actualHexString = "[" + bytesToHexString(bytes) + "]";
 
     if (actualHexString === expectedHexString) {
         debug("PASS: " + testDescription + " should be " + expectedHexString + " and was");
     } else {
@@ skipping 81 matching lines @@
     if (internals)
         debug("Serialized key bytes: " + bytesToHexString(internals.serializeObject(o)));
 }
 
 function shouldEvaluateAs(actual, expectedValue)
 {
     if (typeof expectedValue == "string")
         return shouldBeEqualToString(actual, expectedValue);
     return shouldEvaluateTo(actual, expectedValue);
 }