[runtime] Optimize and unify rest parameters.

src/interpreter/interpreter.cc

 // Copyright 2015 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/interpreter/interpreter.h"
 
 #include "src/ast/prettyprinter.h"
 #include "src/code-factory.h"
 #include "src/compiler.h"
 #include "src/compiler/interpreter-assembler.h"
@@ skipping 1754 matching lines @@
 //
 // Creates a new unmapped arguments object.
 void Interpreter::DoCreateUnmappedArguments(
     compiler::InterpreterAssembler* assembler) {
   Node* closure = __ LoadRegister(Register::function_closure());
   Node* result = __ CallRuntime(Runtime::kNewStrictArguments_Generic, closure);
   __ SetAccumulator(result);
   __ Dispatch();
 }
 
-// CreateRestArguments
+// CreateRestParameter
 //
-// Creates a new rest arguments object starting at |rest_index|.
-void Interpreter::DoCreateRestArguments(
+// Creates a new rest parameter array.
+void Interpreter::DoCreateRestParameter(
     compiler::InterpreterAssembler* assembler) {
+  // TODO(ignition): Use FastNewRestParameterStub here.
   Node* closure = __ LoadRegister(Register::function_closure());
-  Node* constant_pool_index = __ BytecodeOperandIdx(0);
-  Node* rest_index = __ LoadConstantPoolEntry(constant_pool_index);
-  Node* result =
-      __ CallRuntime(Runtime::kNewRestArguments_Generic, closure, rest_index);
+  Node* result = __ CallRuntime(Runtime::kNewRestParameter, closure);
   __ SetAccumulator(result);
   __ Dispatch();
 }
 
 // StackCheck
 //
 // Performs a stack guard check.
 void Interpreter::DoStackCheck(compiler::InterpreterAssembler* assembler) {
   __ StackCheck();
   __ Dispatch();
@@ skipping 121 matching lines @@
   Node* index_reg = __ BytecodeOperandReg(0);
   Node* index = __ LoadRegister(index_reg);
   Node* result = __ CallRuntime(Runtime::kForInStep, index);
   __ SetAccumulator(result);
   __ Dispatch();
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8