Implement function proxies (except for their use as constructors).

src/json.js

 // Copyright 2009 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 36 matching lines @@
           }
         }
       }
     }
   }
   return %_CallFunction(holder, name, val, reviver);
 }
 
 function JSONParse(text, reviver) {
   var unfiltered = %ParseJson(TO_STRING_INLINE(text));
-  if (IS_FUNCTION(reviver)) {
+  if (IS_SPEC_FUNCTION(reviver)) {
     return Revive({'': unfiltered}, '', reviver);
   } else {
     return unfiltered;
   }
 }
 
 function SerializeArray(value, replacer, stack, indent, gap) {
   if (!%PushIfAbsent(stack, value)) {
     throw MakeTypeError('circular_structure', $Array());
   }
@@ skipping 68 matching lines @@
     final = "{}";
   }
   stack.pop();
   return final;
 }
 
 function JSONSerialize(key, holder, replacer, stack, indent, gap) {
   var value = holder[key];
   if (IS_SPEC_OBJECT(value)) {
     var toJSON = value.toJSON;
-    if (IS_FUNCTION(toJSON)) {
+    if (IS_SPEC_FUNCTION(toJSON)) {
       value = %_CallFunction(value, key, toJSON);
     }
   }
-  if (IS_FUNCTION(replacer)) {
+  if (IS_SPEC_FUNCTION(replacer)) {
     value = %_CallFunction(holder, key, value, replacer);
   }
   if (IS_STRING(value)) {
     return %QuoteJSONString(value);
   } else if (IS_NUMBER(value)) {
     return JSON_NUMBER_TO_STRING(value);
   } else if (IS_BOOLEAN(value)) {
     return value ? "true" : "false";
   } else if (IS_NULL(value)) {
     return "null";
@@ skipping 105 matching lines @@
     }
   }
   stack.pop();
   builder.push("}");
 }
 
 
 function BasicJSONSerialize(key, value, stack, builder) {
   if (IS_SPEC_OBJECT(value)) {
     var toJSON = value.toJSON;
-    if (IS_FUNCTION(toJSON)) {
+    if (IS_SPEC_FUNCTION(toJSON)) {
       value = %_CallFunction(value, ToString(key), toJSON);
     }
   }
   if (IS_STRING(value)) {
     builder.push(value !== "" ? %QuoteJSONString(value) : '""');
   } else if (IS_NUMBER(value)) {
     builder.push(JSON_NUMBER_TO_STRING(value));
   } else if (IS_BOOLEAN(value)) {
     builder.push(value ? "true" : "false");
   } else if (IS_NULL(value)) {
@@ skipping 51 matching lines @@
 }
 
 function SetupJSON() {
   InstallFunctions($JSON, DONT_ENUM, $Array(
     "parse", JSONParse,
     "stringify", JSONStringify
   ));
 }
 
 SetupJSON();