Fixed single quote escaping

pkg/csslib/lib/parser.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library csslib.parser;
 
 import 'dart:math' as math;
 
 import 'package:source_maps/span.dart' show SourceFile, Span, FileSpan;
 
@@ skipping 1476 matching lines @@
           break;
         case TokenKind.INTEGER:
           termToken = _next();
           value = int.parse(termToken.text);
           break;
         case TokenKind.DOUBLE:
           termToken = _next();
           value = double.parse(termToken.text);
           break;
         case TokenKind.SINGLE_QUOTE:
+          value = processQuotedString(false);
+          value = "'${_escapeString(value, single: true)}'";
+          return new LiteralTerm(value, value, _makeSpan(start));
         case TokenKind.DOUBLE_QUOTE:
           value = processQuotedString(false);
           value = '"${_escapeString(value)}"';
           return new LiteralTerm(value, value, _makeSpan(start));
         case TokenKind.IDENTIFIER:
           value = identifier();   // Snarf up the ident we'll remap, maybe.
           break;
         default:
           keepParsing = false;
       }
@@ skipping 615 matching lines @@
       return _parseHex(" ${processTerm().text}", _makeSpan(start));
     case TokenKind.INTEGER:
       t = _next();
       value = int.parse("${unary}${t.text}");
       break;
     case TokenKind.DOUBLE:
       t = _next();
       value = double.parse("${unary}${t.text}");
       break;
     case TokenKind.SINGLE_QUOTE:
+      value = processQuotedString(false);
+      value = "'${_escapeString(value, single: true)}'";
+      return new LiteralTerm(value, value, _makeSpan(start));
     case TokenKind.DOUBLE_QUOTE:
       value = processQuotedString(false);
       value = '"${_escapeString(value)}"';
       return new LiteralTerm(value, value, _makeSpan(start));
     case TokenKind.LPAREN:
       _next();
 
       GroupTerm group = new GroupTerm(_makeSpan(start));
 
       var term;
@@ skipping 516 matching lines @@
 
     if (replace != null && result == null) {
       result = new StringBuffer(text.substring(0, i));
     }
 
     if (result != null) result.write(replace != null ? replace : text[i]);
   }
 
   return result == null ? text : result.toString();
 }