[es6] parse destructuring assignment

src/parser.cc

Index: src/parser.cc
diff --git a/src/parser.cc b/src/parser.cc
index a961f9140386b67cf84dbfb26b62341d37685dab..92f173198e56457491aae286c45fc36a3ca2377a 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -2594,6 +2594,7 @@ Statement* Parser::ParseExpressionOrLabelledStatement(
   }
 
   bool starts_with_idenfifier = peek_any_identifier();
+
   Expression* expr = ParseExpression(true, CHECK_OK);
   if (peek() == Token::COLON && starts_with_idenfifier && expr != NULL &&
       expr->AsVariableProxy() != NULL &&
@@ -3430,6 +3431,17 @@ 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 ::