[es6] Re-implement rest parameters via desugaring.

src/hydrogen.cc

 // Copyright 2013 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/hydrogen.h"
 
 #include <sstream>
 
 #include "src/allocation-site-scopes.h"
 #include "src/ast-numbering.h"
@@ skipping 4640 matching lines @@
 
   AddInstruction(arguments_object);
   graph()->SetArgumentsObject(arguments_object);
 
   // Handle the arguments and arguments shadow variables specially (they do
   // not have declarations).
   if (scope->arguments() != NULL) {
     environment()->Bind(scope->arguments(), graph()->GetArgumentsObject());
   }
 
-  int rest_index;
-  Variable* rest = scope->rest_parameter(&rest_index);
-  if (rest) {
-    return Bailout(kRestParameter);
-  }
-
   if (scope->this_function_var() != nullptr ||
       scope->new_target_var() != nullptr) {
     return Bailout(kSuperReference);
   }
 
   // Trace the call.
   if (FLAG_trace && top_info()->IsOptimizing()) {
     Add<HCallRuntime>(Runtime::FunctionForId(Runtime::kTraceEnter), 0);
   }
 }
@@ skipping 8780 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8