Implement ES6 rest parameters

src/scopes.h

 // Copyright 2012 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.
 
 #ifndef V8_SCOPES_H_
 #define V8_SCOPES_H_
 
 #include "src/ast.h"
 #include "src/zone.h"
 
@@ skipping 363 matching lines @@
 
   int num_parameters() const { return params_.length(); }
 
   // A function can have at most one rest parameter. Returns Variable* or NULL.
   Variable* rest_parameter(int* index) const {
     *index = rest_index_;
     if (rest_index_ < 0) return NULL;
     return rest_parameter_;
   }
 
+  bool has_rest_parameter() const {
+    return rest_index_ >= 0;
+  }
+
   bool is_simple_parameter_list() const {
     DCHECK(is_function_scope());
     if (rest_index_ >= 0) return false;
     return true;
   }
 
   // The local variable 'arguments' if we need to allocate it; NULL otherwise.
   Variable* arguments() const { return arguments_; }
 
   // Declarations list.
@@ skipping 308 matching lines @@
                    Scope* outer_scope,
                    Handle<ScopeInfo> scope_info);
 
   AstValueFactory* ast_value_factory_;
   Zone* zone_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_SCOPES_H_