[es6] Re-implement rest parameters via desugaring.

src/compiler/ast-graph-builder.cc

Index: src/compiler/ast-graph-builder.cc
diff --git a/src/compiler/ast-graph-builder.cc b/src/compiler/ast-graph-builder.cc
index 10abec7b8824741217a09e39e69e8e35b4a9224c..4043c4ab2b7931b85153a10f4b2cf6f1022b0114 100644
--- a/src/compiler/ast-graph-builder.cc
+++ b/src/compiler/ast-graph-builder.cc
@@ -568,11 +568,6 @@ void AstGraphBuilder::CreateGraphBody(bool stack_check) {
   // Build the arguments object if it is used.
   BuildArgumentsObject(scope->arguments());
 
-  // Build rest arguments array if it is used.
-  int rest_index;
-  Variable* rest_parameter = scope->rest_parameter(&rest_index);
-  BuildRestArgumentsArray(rest_parameter, rest_index);
-
   // Build assignment to {.this_function} variable if it is used.
   BuildThisFunctionVariable(scope->this_function_var());
 
@@ -3192,24 +3187,6 @@ Node* AstGraphBuilder::BuildArgumentsObject(Variable* arguments) {
 }
 
 
-Node* AstGraphBuilder::BuildRestArgumentsArray(Variable* rest, int index) {
-  if (rest == NULL) return NULL;
-
-  DCHECK(index >= 0);
-  const Operator* op = javascript()->CallRuntime(Runtime::kNewRestParamSlow, 2);
-  Node* object = NewNode(op, jsgraph()->SmiConstant(index),
-                         jsgraph()->SmiConstant(language_mode()));
-
-  // Assign the object to the rest parameter variable.
-  DCHECK(rest->IsContextSlot() || rest->IsStackAllocated());
-  // This should never lazy deopt, so it is fine to send invalid bailout id.
-  FrameStateBeforeAndAfter states(this, BailoutId::None());
-  BuildVariableAssignment(rest, object, Token::ASSIGN, VectorSlotPair(),
-                          BailoutId::None(), states);
-  return object;
-}
-
-
 Node* AstGraphBuilder::BuildThisFunctionVariable(Variable* this_function_var) {
   if (this_function_var == nullptr) return nullptr;