Remove arguments shadow from scopes, stop rewriting parameters.

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

Index: arguments/src/x64/full-codegen-x64.cc
diff --git a/arguments/src/x64/full-codegen-x64.cc b/arguments/src/x64/full-codegen-x64.cc
index 6625afc6f1ebde22e6dcf0ee55bce17a4cc35ea8..97e0760a6351f5fd3cf7d400977146c890d7c8c4 100644
--- a/arguments/src/x64/full-codegen-x64.cc
+++ b/arguments/src/x64/full-codegen-x64.cc
@@ -201,12 +201,6 @@ void FullCodeGenerator::Generate(CompilationInfo* info) {
     ArgumentsAccessStub stub(ArgumentsAccessStub::NEW_OBJECT);
     __ CallStub(&stub);
 
-    Variable* arguments_shadow = scope()->arguments_shadow();
-    if (arguments_shadow != NULL) {
-      // Store new arguments object in both "arguments" and ".arguments" slots.
-      __ movq(rcx, rax);
-      Move(arguments_shadow->AsSlot(), rcx, rbx, rdx);
-    }
     Move(arguments->AsSlot(), rax, rbx, rdx);
   }