[runtime] Rewrite Function.prototype.toString in C++.

src/builtins.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/builtins.h"
 
 #include "src/api.h"
 #include "src/api-natives.h"
 #include "src/arguments.h"
 #include "src/base/once.h"
@@ skipping 1759 matching lines @@
   }
   Handle<JSReceiver> receiver = args.at<JSReceiver>(0);
   Handle<Object> hint = args.at<Object>(1);
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                      JSDate::ToPrimitive(receiver, hint));
   return *result;
 }
 
 
+// ES6 section 19.2.3.5 Function.prototype.toString ( )
+BUILTIN(FunctionPrototypeToString) {
+  HandleScope scope(isolate);
+  Handle<Object> receiver = args.receiver();
+
+  if (receiver->IsJSFunction()) {
+    return *JSFunction::ToString(Handle<JSFunction>::cast(receiver));
+  }
+  THROW_NEW_ERROR_RETURN_FAILURE(
+      isolate, NewTypeError(MessageTemplate::kNotGeneric,
+                            isolate->factory()->NewStringFromAsciiChecked(
+                                "Function.prototype.toString")));
+}
+
+
 // ES6 section 19.4.1.1 Symbol ( [ description ] ) for the [[Call]] case.
 BUILTIN(SymbolConstructor) {
   HandleScope scope(isolate);
   DCHECK_EQ(2, args.length());
   Handle<Symbol> result = isolate->factory()->NewSymbol();
   Handle<Object> description = args.at<Object>(1);
   if (!description->IsUndefined()) {
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, description,
                                        Object::ToString(isolate, description));
     result->set_name(*description);
@@ skipping 716 matching lines @@
 BUILTIN_LIST_C(DEFINE_BUILTIN_ACCESSOR_C)
 BUILTIN_LIST_A(DEFINE_BUILTIN_ACCESSOR_A)
 BUILTIN_LIST_H(DEFINE_BUILTIN_ACCESSOR_H)
 BUILTIN_LIST_DEBUG_A(DEFINE_BUILTIN_ACCESSOR_A)
 #undef DEFINE_BUILTIN_ACCESSOR_C
 #undef DEFINE_BUILTIN_ACCESSOR_A
 
 
 }  // namespace internal
 }  // namespace v8