Fix bug in parser that allows "(foo):42" as a labeled statement.

src/parser.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1674 matching lines @@
 
   return false;
 }
 
 
 Statement* Parser::ParseExpressionOrLabelledStatement(ZoneStringList* labels,
                                                       bool* ok) {
   // ExpressionStatement | LabelledStatement ::
   //   Expression ';'
   //   Identifier ':' Statement
-
+  bool starts_with_idenfifier = (peek() == Token::IDENTIFIER);
   Expression* expr = ParseExpression(true, CHECK_OK);
-  if (peek() == Token::COLON && expr &&
+  if (peek() == Token::COLON && starts_with_idenfifier && expr &&
       expr->AsVariableProxy() != NULL &&
       !expr->AsVariableProxy()->is_this()) {
+    // Expression is a single identifier, and not, e.g., a parenthesized
+    // identifier.
     VariableProxy* var = expr->AsVariableProxy();
     Handle<String> label = var->name();
     // TODO(1240780): We don't check for redeclaration of labels
     // during preparsing since keeping track of the set of active
     // labels requires nontrivial changes to the way scopes are
     // structured.  However, these are probably changes we want to
     // make later anyway so we should go back and fix this then.
     if (ContainsLabel(labels, label) || TargetStackContainsLabel(label)) {
       SmartPointer<char> c_string = label->ToCString(DISALLOW_NULLS);
       const char* elms[2] = { "Label", *c_string };
@@ skipping 3022 matching lines @@
       Handle<String> source = Handle<String>(String::cast(script->source()));
       result = parser.ParseProgram(source, info->is_global());
     }
   }
 
   info->SetFunction(result);
   return (result != NULL);
 }
 
 } }  // namespace v8::internal