[es6] implement destructuring assignment

src/crankshaft/typing.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/crankshaft/typing.h"
 
 #include "src/frames.h"
 #include "src/frames-inl.h"
 #include "src/ostreams.h"
 #include "src/parser.h"  // for CompileTimeValue; TODO(rossberg): should move
@@ skipping 379 matching lines @@
   NarrowType(expr, Bounds(type));
 }
 
 
 void AstTyper::VisitRegExpLiteral(RegExpLiteral* expr) {
   // TODO(rossberg): Reintroduce RegExp type.
   NarrowType(expr, Bounds(Type::Object(zone())));
 }
 
 
+void AstTyper::VisitAssignmentPattern(AssignmentPattern* expr) {
+  Visit(expr->expression());
+}
+
+
 void AstTyper::VisitObjectLiteral(ObjectLiteral* expr) {
   ZoneList<ObjectLiteral::Property*>* properties = expr->properties();
   for (int i = 0; i < properties->length(); ++i) {
     ObjectLiteral::Property* prop = properties->at(i);
 
     // Collect type feedback.
     if ((prop->kind() == ObjectLiteral::Property::MATERIALIZED_LITERAL &&
         !CompileTimeValue::IsCompileTimeValue(prop->value())) ||
         prop->kind() == ObjectLiteral::Property::COMPUTED) {
       if (!prop->is_computed_name() &&
@@ skipping 403 matching lines @@
 void AstTyper::VisitImportDeclaration(ImportDeclaration* declaration) {
 }
 
 
 void AstTyper::VisitExportDeclaration(ExportDeclaration* declaration) {
 }
 
 
 }  // namespace internal
 }  // namespace v8