Canvas2D Performance: fix the bottleneck of hasInstance during JS binding -- overloading

Source/bindings/scripts/v8_methods.py

 # Copyright (C) 2013 Google Inc. All rights reserved.
 #
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@@ skipping 222 matching lines @@
         # FIXME: Remove generic 'Dictionary' special-casing
         'is_dictionary': idl_type.is_dictionary or idl_type.base_type == 'Dictionary',
         'is_nullable': idl_type.is_nullable,
         'is_optional': argument.is_optional,
         'is_variadic_wrapper_type': is_variadic_wrapper_type,
         'is_wrapper_type': idl_type.is_wrapper_type,
         'name': argument.name,
         'private_script_cpp_value_to_v8_value': idl_type.cpp_value_to_v8_value(
             argument.name, isolate='scriptState->isolate()',
             creation_context='scriptState->context()->Global()'),
+        # 'type_checked_already': False,
         'v8_set_return_value': v8_set_return_value(interface.name, method, this_cpp_value),
         'v8_set_return_value_for_main_world': v8_set_return_value(interface.name, method, this_cpp_value, for_main_world=True),
         'v8_value_to_local_cpp_value': v8_value_to_local_cpp_value(argument, index, type_checked, return_promise=method.returns_promise),
         'vector_type': v8_types.cpp_ptr_type('Vector', 'HeapVector', idl_type.gc_type),
     }
 
 
 def argument_declarations_for_private_script(interface, method):
     argument_declarations = ['LocalFrame* frame']
     argument_declarations.append('%s* holderImpl' % interface.name)
@@ skipping 196 matching lines @@
 
 IdlOperation.returns_promise = property(method_returns_promise)
 
 
 def argument_conversion_needs_exception_state(method, argument):
     idl_type = argument.idl_type
     return (idl_type.v8_conversion_needs_exception_state or
             argument.is_variadic or
             (method.returns_promise and (idl_type.is_string_type or
                                          idl_type.is_enum)))