IDL: Support callback function types in overload resolution

Source/bindings/scripts/v8_interface.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 # coding=utf-8
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
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 #     * 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 824 matching lines @@
     # • an interface type that V implements
     # (Unlike most of these tests, this can return multiple methods, since we
     #  test if it implements an interface. Thus we need a for loop, not a next.)
     # (We distinguish wrapper types from built-in interface types.)
     for idl_type, method in ((idl_type, method)
                              for idl_type, method in idl_types_methods
                              if idl_type.is_wrapper_type):
         test = 'V8{idl_type}::hasInstance({cpp_value}, info.GetIsolate())'.format(idl_type=idl_type.base_type, cpp_value=cpp_value)
         yield test, method
 
-    # 8. Otherwise: if V is any kind of object except for a native Date object,
+    # 13. Otherwise: if IsCallable(V) is true, and there is an entry in S that
+    # has one of the following types at position i of its type list,
+    # • a callback function type
+    # ...
+    #
+    # FIXME:
+    # We test for functions rather than callability, which isn't strictly the
+    # same thing.
+    try:
+        method = next(method for idl_type, method in idl_types_methods
+                      if idl_type.is_callback_function)
+        test = '%s->IsFunction()' % cpp_value
+        yield test, method
+    except StopIteration:
+        pass
+
+    # 14. Otherwise: if V is any kind of object except for a native Date object,
+    # a native RegExp object, and there is an entry in S that has one of the
+    # following types at position i of its type list,
+    # • a sequence type
+    # ...
+    #
+    # 15. Otherwise: if V is any kind of object except for a native Date object,
     # a native RegExp object, and there is an entry in S that has one of the
     # following types at position i of its type list,
     # • an array type
-    # • a sequence type
     # ...
     # • a dictionary
     #
     # FIXME:
     # We don't strictly follow the algorithm here. The algorithm says "remove
     # all other entries" if there is "one entry" matching, but we yield all
     # entries to support following constructors:
     # [constructor(sequence<DOMString> arg), constructor(Dictionary arg)]
     # interface I { ... }
     # (Need to check array types before objects because an array is an object)
@@ skipping 358 matching lines @@
         deleter = next(
             method
             for method in interface.operations
             if ('deleter' in method.specials and
                 len(method.arguments) == 1 and
                 str(method.arguments[0].idl_type) == 'DOMString'))
     except StopIteration:
         return None
 
     return property_deleter(deleter)