Check for compile-time constants in DartCompiler

samples/clock/Balls.dart

 // Copyright (c) 2011, 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.
 
 class Balls {
   static final double RADIUS2 = Ball.RADIUS * Ball.RADIUS;
 
   // TODO: "static const Array<String> PNGS" doesn't parse
-  static final List<String> PNGS = ["images/ball-d9d9d9.png",
+  static final List<String> PNGS = const ["images/ball-d9d9d9.png",
       "images/ball-009a49.png", "images/ball-13acfa.png",
       "images/ball-265897.png", "images/ball-b6b4b5.png",
       "images/ball-c0000b.png", "images/ball-c9c9c9.png"];
 
   HTMLDivElement root;
   int lastTime;
   List<Ball> balls;
 
   Balls() :
       lastTime = Util.currentTimeMillis(),
@@ skipping 65 matching lines @@
     double ndx = (nb0x - nb1x).abs();
     double ndy = (nb0y - nb1y).abs();
     double nd2 = ndx * ndx + ndy * ndy;
     return nd2;
   }
 
   void add(int x, int y, int color) {
     balls.add(new Ball(root, x, y, color));
   }
 }