Correctly match and print strings with escaped values

lib/src/core_matchers.dart

Index: lib/src/core_matchers.dart
diff --git a/lib/src/core_matchers.dart b/lib/src/core_matchers.dart
index abecb769856fa31f053c2a0202c904948d5f30e9..3963bf1f25f12aac5e4592bd42394ebc8058b934 100644
--- a/lib/src/core_matchers.dart
+++ b/lib/src/core_matchers.dart
@@ -5,6 +5,7 @@
 library matcher.core_matchers;
 
 import 'description.dart';
+import 'escape.dart';
 import 'interfaces.dart';
 import 'util.dart';
 
@@ -297,8 +298,8 @@ class _StringEqualsMatcher extends Matcher {
     } else {
       var buff = new StringBuffer();
       buff.write('is different.');
-      var escapedItem = _escape(item);
-      var escapedValue = _escape(_value);
+      var escapedItem = escape(item);
+      var escapedValue = escape(_value);
       int minLength = escapedItem.length < escapedValue.length
           ? escapedItem.length
           : escapedValue.length;
@@ -334,9 +335,6 @@ class _StringEqualsMatcher extends Matcher {
     }
   }
 
-  static String _escape(String s) =>
-      s.replaceAll('\n', '\\n').replaceAll('\r', '\\r').replaceAll('\t', '\\t');
-
   static void _writeLeading(StringBuffer buff, String s, int start) {
     if (start > 10) {
       buff.write('... ');