[es6] parse destructuring assignment

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index a7a31e7173593e67036cf4ffb9de14bb79f2e478..d4086d6ad75d4f23c3922358a74ca394fd942630 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -3495,6 +3495,17 @@ Statement* Parser::DesugarLexicalBindingsInForStatement(
 }
 
 
+Expression* Parser::DesugarDestructuringAssignment(Expression* expr) {
+  // TODO(caitp): implement the desugaring
+  DCHECK(expr->IsAssignment());
+  Assignment* assign = expr->AsAssignment();
+  while (assign->value()->IsAssignment()) {
+    assign = assign->value()->AsAssignment();
+  }
+  return assign->value();
+}
+
+
 Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
                                      bool* ok) {
   // ForStatement ::