[es6] implement destructuring assignment

src/ast-numbering.cc

Index: src/ast-numbering.cc
diff --git a/src/ast-numbering.cc b/src/ast-numbering.cc
index 8479191b5e9b44cfd00cf1b5010401f4f666966b..f9f7438f572dfaa7dac43869eaf892cb9b8aa471 100644
--- a/src/ast-numbering.cc
+++ b/src/ast-numbering.cc
@@ -348,6 +348,12 @@ void AstNumberingVisitor::VisitProperty(Property* node) {
 void AstNumberingVisitor::VisitAssignment(Assignment* node) {
   IncrementNodeCount();
   node->set_base_id(ReserveIdRange(Assignment::num_ids()));
+
+  AssignmentPattern* pattern = node->target()->AsAssignmentPattern();
+  if (pattern && pattern->is_rewritten()) {
+    return Visit(pattern->expression());
+  }
+
   if (node->is_compound()) VisitBinaryOperation(node->binary_operation());
   VisitReference(node->target());
   Visit(node->value());
@@ -473,6 +479,12 @@ void AstNumberingVisitor::VisitClassLiteral(ClassLiteral* node) {
 }
 
 
+void AstNumberingVisitor::VisitAssignmentPattern(AssignmentPattern* node) {
+  IncrementNodeCount();
+  Visit(node->expression());
+}
+
+
 void AstNumberingVisitor::VisitObjectLiteral(ObjectLiteral* node) {
   IncrementNodeCount();
   node->set_base_id(ReserveIdRange(node->num_ids()));