Partial revert of rest parameter desugaring.

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index 1b65345f29b2cc2a95ad87e018d47d7e1128c4e7..1cc18044fd298189403d1b54d6c3c3de6d49f9e4 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -249,6 +249,29 @@ void FullCodeGenerator::Generate() {
     SetVar(new_target_var, rdx, rbx, rcx);
   }
 
+  // Possibly allocate RestParameters
+  int rest_index;
+  Variable* rest_param = scope()->rest_parameter(&rest_index);
+  if (rest_param) {
+    Comment cmnt(masm_, "[ Allocate rest parameter array");
+
+    int num_parameters = info->scope()->num_parameters();
+    int offset = num_parameters * kPointerSize;
+
+    __ leap(rdx,
+            Operand(rbp, StandardFrameConstants::kCallerSPOffset + offset));
+    __ Push(rdx);
+    __ Push(Smi::FromInt(num_parameters));
+    __ Push(Smi::FromInt(rest_index));
+    __ Push(Smi::FromInt(language_mode()));
+    function_in_register = false;
+
+    RestParamAccessStub stub(isolate());
+    __ CallStub(&stub);
+
+    SetVar(rest_param, rax, rbx, rdx);
+  }
+
   // Possibly allocate an arguments object.
   Variable* arguments = scope()->arguments();
   if (arguments != NULL) {