Partial revert of rest parameter desugaring.

src/ast/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_AST_SCOPES_H_
 #define V8_AST_SCOPES_H_
 
 #include "src/ast/ast.h"
 #include "src/hashmap.h"
 #include "src/pending-compilation-error-handler.h"
@@ skipping 403 matching lines @@
   Variable* parameter(int index) const {
     DCHECK(is_function_scope());
     return params_[index];
   }
 
   // Returns the default function arity excluding default or rest parameters.
   int default_function_length() const { return arity_; }
 
   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 has_simple_parameters() const {
     return has_simple_parameters_;
   }
 
   // TODO(caitp): manage this state in a better way. PreParser must be able to
   // communicate that the scope is non-simple, without allocating any parameters
   // as the Parser does. This is necessary to ensure that TC39's proposed early
   // error can be reported consistently regardless of whether lazily parsed or
   // not.
   void SetHasNonSimpleParameters() {
@@ skipping 241 matching lines @@
 
   // Computed via AllocateVariables; function, block and catch scopes only.
   int num_stack_slots_;
   int num_heap_slots_;
   int num_global_slots_;
 
   // Info about the parameter list of a function.
   int arity_;
   bool has_simple_parameters_;
   Variable* rest_parameter_;
+  int rest_index_;
 
   // Serialized scope info support.
   Handle<ScopeInfo> scope_info_;
   bool already_resolved() { return already_resolved_; }
 
   // Create a non-local variable with a given name.
   // These variables are looked up dynamically at runtime.
   Variable* NonLocal(const AstRawString* name, VariableMode mode);
 
   // Variable resolution.
@@ skipping 126 matching lines @@
 
   // For tracking which classes are declared consecutively. Needed for strong
   // mode.
   int class_declaration_group_start_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPES_H_