[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 4631 matching lines @@
     environment()->Bind(i, undefined_constant);
   }
 
   // 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);
   }
 }
 
 
 void HOptimizedGraphBuilder::VisitStatements(ZoneList<Statement*>* statements) {
   for (int i = 0; i < statements->length(); i++) {
     Statement* stmt = statements->at(i);
@@ skipping 1017 matching lines @@
           new(zone()) HLoadContextSlot(context, variable->index(), mode);
       return ast_context()->ReturnInstruction(instr, expr->id());
     }
 
     case VariableLocation::LOOKUP:
       return Bailout(kReferenceToAVariableWhichRequiresDynamicLookup);
   }
 }
 
 
+void HOptimizedGraphBuilder::VisitRestParameter(RestParameter* node) {
+  UNREACHABLE();
+}
+
+
 void HOptimizedGraphBuilder::VisitLiteral(Literal* expr) {
   DCHECK(!HasStackOverflow());
   DCHECK(current_block() != NULL);
   DCHECK(current_block()->HasPredecessor());
   HConstant* instr = New<HConstant>(expr->value());
   return ast_context()->ReturnInstruction(instr, expr->id());
 }
 
 
 void HOptimizedGraphBuilder::VisitRegExpLiteral(RegExpLiteral* expr) {
@@ skipping 7730 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8