[es6] re-implement rest parameters via desugaring

src/runtime/runtime-scopes.cc

 // Copyright 2014 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/v8.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/frames-inl.h"
 #include "src/messages.h"
@@ skipping 508 matching lines @@
 RUNTIME_FUNCTION(Runtime_NewStrictArguments) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 3);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, callee, 0)
   Object** parameters = reinterpret_cast<Object**>(args[1]);
   CONVERT_SMI_ARG_CHECKED(argument_count, 2);
   return *NewStrictArguments(isolate, callee, parameters, argument_count);
 }
 
 
-static Handle<JSArray> NewRestParam(Isolate* isolate, Object** parameters,
-                                    int num_params, int rest_index,
-                                    LanguageMode language_mode) {
-  parameters -= rest_index;
-  int num_elements = std::max(0, num_params - rest_index);
-  Handle<FixedArray> elements =
-      isolate->factory()->NewUninitializedFixedArray(num_elements);
-  for (int i = 0; i < num_elements; ++i) {
-    elements->set(i, *--parameters);
-  }
-  return isolate->factory()->NewJSArrayWithElements(
-      elements, FAST_ELEMENTS, num_elements, strength(language_mode));
-}
-
-
-RUNTIME_FUNCTION(Runtime_NewRestParam) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 4);
-  Object** parameters = reinterpret_cast<Object**>(args[0]);
-  CONVERT_SMI_ARG_CHECKED(num_params, 1);
-  CONVERT_SMI_ARG_CHECKED(rest_index, 2);
-  CONVERT_SMI_ARG_CHECKED(language_mode, 3);
-
-  return *NewRestParam(isolate, parameters, num_params, rest_index,
-                       static_cast<LanguageMode>(language_mode));
-}
-
-
-RUNTIME_FUNCTION(Runtime_NewRestParamSlow) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 2);
-  CONVERT_SMI_ARG_CHECKED(rest_index, 0);
-  CONVERT_SMI_ARG_CHECKED(language_mode, 1);
-
-  JavaScriptFrameIterator it(isolate);
-
-  // Find the frame that holds the actual arguments passed to the function.
-  it.AdvanceToArgumentsFrame();
-  JavaScriptFrame* frame = it.frame();
-
-  int argument_count = frame->GetArgumentsLength();
-  Object** parameters = reinterpret_cast<Object**>(frame->GetParameterSlot(-1));
-
-  return *NewRestParam(isolate, parameters, argument_count, rest_index,
-                       static_cast<LanguageMode>(language_mode));
-}
-
-
 RUNTIME_FUNCTION(Runtime_NewClosureFromStubFailure) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(SharedFunctionInfo, shared, 0);
   Handle<Context> context(isolate->context());
   PretenureFlag pretenure_flag = NOT_TENURED;
   return *isolate->factory()->NewFunctionFromSharedFunctionInfo(shared, context,
                                                                 pretenure_flag);
 }
 
@@ skipping 563 matching lines @@
   return Smi::FromInt(frame->GetArgumentsLength());
 }
 
 
 RUNTIME_FUNCTION(Runtime_Arguments) {
   SealHandleScope shs(isolate);
   return __RT_impl_Runtime_GetArgumentsProperty(args, isolate);
 }
 }  // namespace internal
 }  // namespace v8