Refactored custom call IC generators:

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index ae7d2c2a97201de87ca7bc89e547462d1f8cf4e3..ad151041528b3a7e4b75146eda063f7f68e09549 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -2530,7 +2530,13 @@ FunctionTemplateInfo* SharedFunctionInfo::get_api_func_data() {
 
 
 bool SharedFunctionInfo::HasCustomCallGenerator() {
-  return function_data()->IsProxy();
+  return function_data()->IsSmi();
+}
+
+
+int SharedFunctionInfo::custom_call_generator_id() {
+  ASSERT(HasCustomCallGenerator());
+  return Smi::cast(function_data())->value();
 }