Improve the display of data: URIs in stack traces.

test/frame_test.dart

Index: test/frame_test.dart
diff --git a/test/frame_test.dart b/test/frame_test.dart
index 1233cbf85b1b002772863e70a4e9a7fead3d7b2e..63035e0e692867676d52fc060f96f9cd87f5be12 100644
--- a/test/frame_test.dart
+++ b/test/frame_test.dart
@@ -503,6 +503,12 @@ void main() {
       expect(new Frame.parseVM('#0 Foo (foo/bar.dart:0:0)').library,
           equals(path.join('foo', 'bar.dart')));
     });
+
+    test('truncates data: URIs', () {
+      var frame = new Frame.parseVM(
+          '#0 Foo (data:application/dart;charset=utf-8,blah:0:0)');
+      expect(frame.library, equals('data:...'));
+    });
   });
 
   group('.location', () {