API functions returning Promises should not throw exceptions.

Source/bindings/tests/idls/TestObject.idl

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 313 matching lines @@
     // Callback interface types
     void voidMethodTestCallbackInterfaceArg(TestCallbackInterface testCallbackInterfaceArg);
     void voidMethodOptionalTestCallbackInterfaceArg(optional TestCallbackInterface optionalTestCallbackInterfaceArg);
     void voidMethodTestCallbackInterfaceOrNullArg(TestCallbackInterface? testCallbackInterfaceArg);
     // Enumerations
     TestEnum testEnumMethod();
     void voidMethodTestEnumArg(TestEnum testEnumTypeArg);
     // Exceptional types
     Dictionary dictionaryMethod();
     NodeFilter nodeFilterMethod();
-    Promise promiseMethod();
+    Promise promiseMethod(long arg1, Dictionary arg2, DOMString arg3, DOMString... variadic);
+    Promise promiseMethodWithoutExceptionState(Dictionary arg1);
     SerializedScriptValue serializedScriptValueMethod();
     XPathNSResolver xPathNSResolverMethod();
     void voidMethodDictionaryArg(Dictionary dictionaryArg);
     void voidMethodEventListenerArg(EventListener eventListenerArg);
     void voidMethodNodeFilterArg(NodeFilter nodeFilterArg);
     void voidMethodPromiseArg(Promise promiseArg);
     void voidMethodSerializedScriptValueArg(SerializedScriptValue serializedScriptValueArg);
     void voidMethodXPathNSResolverArg(XPathNSResolver xPathNSResolverArg);
     void voidMethodDictionarySequenceArg(sequence<Dictionary> dictionarySequenceArg);
 
@@ skipping 116 matching lines @@
     // [WillBeGarbageCollected]
     void voidMethodTestInterfaceWillBeGarbageCollectedSequenceArg(sequence<TestInterfaceWillBeGarbageCollected> testInterfaceWillBeGarbageCollectedSequenceArg);
     void voidMethodTestInterfaceWillBeGarbageCollectedArrayArg(TestInterfaceWillBeGarbageCollected[] testInterfaceWillBeGarbageCollectedArrayArg);
 
     // Extended attributes on referenced interfaces
     // (not self; self-reference tests at interface themselves)
     attribute TestInterface testInterfaceAttribute; // [ImplementedAs]
     attribute TestInterfaceWillBeGarbageCollected testInterfaceWillBeGarbageCollectedAttribute; // [WillBeGarbageCollected]
     attribute TestInterfaceWillBeGarbageCollected? testInterfaceWillBeGarbageCollectedOrNullAttribute; // [WillBeGarbageCollected]
 };