Add test of unittests.

tests/compiler/dart2js/sourcemaps/colors.dart

 // Copyright (c) 2015, 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.
 
 /// Utility library for creating web colors.
 
-library colors;
+library sourcemaps.colors;
 
 /// A web color.
 abstract class Color {
   /// The css code for the color.
   String get toCss;
 }
 
 /// A web color defined as RGB.
 class RGB implements Color {
   final double r;
@@ skipping 94 matching lines @@
         return new RGB(p, q, v);
       case 4:
         return new RGB(t, p, v);
       default:    // case 5:
         return new RGB(v, p, q);
     }
   }
 
   String toString() => 'hsv($h,$s,$v)';
 }