[bindings] Support is_explicit_nullable for method arguments.

Source/bindings/tests/idls/core/TestInterface.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
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@@ skipping 88 matching lines @@
 
     [Exposed=(Window,ServiceWorker)] void windowAndServiceWorkerExposedMethod();
 
     void voidMethodPartialOverload();
     void voidMethodPartialOverload(double doubleArg);
     static void staticVoidMethodPartialOverload();
 
     Promise promiseMethodPartialOverload();
     Promise promiseMethodPartialOverload(Window window);
     static Promise staticPromiseMethodPartialOverload();
+    void methodWithExplicitNullableArgument(optional object[]? arguments);

[Jens Widell, 2015/03/02 07:53:13]

I think this rather belongs in TestObject.idl, where we have numerous tests for
specific method argument types already.

 };
 
 TestInterface implements TestImplements;
 // TestInterface implements TestImplements2; // at implement*ed* interface
 TestInterface implements TestImplements3;