lib/utf: remove codepointsToString

point folks to use String.fromCharCodes

Review URL: https://codereview.chromium.org//13493020

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/source_maps@21151 260f80e4-7a28-3924-810f-c04153c831b5
diff --git a/lib/span.dart b/lib/span.dart
index 1982994..fd302bc 100644
--- a/lib/span.dart
+++ b/lib/span.dart
@@ -5,7 +5,7 @@
 /// Dart classes representing the souce spans and source files.
 library source_maps.span;
 
-import 'dart:utf' show stringToCodepoints, codepointsToString;
+import 'dart:utf' show stringToCodepoints;
 import 'dart:math' show min;
 
 import 'src/utils.dart';
@@ -232,7 +232,7 @@
 
   /// Gets the text at the given offsets.
   String getText(int start, [int end]) {
-    return codepointsToString(_decodedChars.sublist(start, end));
+    return new String.fromCharCodes(_decodedChars.sublist(start, end));
   }
 
   /// Create a pretty string representation from a span.