[es6] implement destructuring assignment

src/ast.cc

 // 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.
 
 #include "src/ast.h"
 
 #include <cmath>  // For isfinite.
 #include "src/builtins.h"
 #include "src/code-stubs.h"
 #include "src/contexts.h"
@@ skipping 131 matching lines @@
 
 
 Assignment::Assignment(Zone* zone, Token::Value op, Expression* target,
                        Expression* value, int pos)
     : Expression(zone, pos),
       bit_field_(
           IsUninitializedField::encode(false) | KeyTypeField::encode(ELEMENT) |
           StoreModeField::encode(STANDARD_STORE) | TokenField::encode(op)),
       target_(target),
       value_(value),
+      destructuring_assignment_(nullptr),
       binary_operation_(NULL) {}
 
 
 void Assignment::AssignFeedbackVectorSlots(Isolate* isolate,
                                            FeedbackVectorSpec* spec,
                                            FeedbackVectorSlotCache* cache) {
   AssignVectorSlots(target(), spec, &slot_);
 }
 
 
@@ skipping 981 matching lines @@
 bool Literal::Match(void* literal1, void* literal2) {
   const AstValue* x = static_cast<Literal*>(literal1)->raw_value();
   const AstValue* y = static_cast<Literal*>(literal2)->raw_value();
   return (x->IsString() && y->IsString() && x->AsString() == y->AsString()) ||
          (x->IsNumber() && y->IsNumber() && x->AsNumber() == y->AsNumber());
 }
 
 
 }  // namespace internal
 }  // namespace v8