Implement modular compilation

test/codegen/sunflower/sunflower.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.
 
 library sunflower;
 
+import 'dart:html';
 import 'dart:math';
 
 import 'circle.dart';
-import 'dom.dart';
 import 'painter.dart';
 
 const SEED_RADIUS = 2;
 const SCALE_FACTOR = 4;
 const MAX_D = 300;
 const centerX = MAX_D / 2;
 const centerY = centerX;
 
 Element querySelector(String selector) => document.querySelector(selector);
 final canvas = querySelector("#canvas") as CanvasElement;
@@ skipping 13 matching lines @@
 void draw() {
   seeds = int.parse(slider.value);
   context.clearRect(0, 0, MAX_D, MAX_D);
   for (var i = 0; i < seeds; i++) {
     final theta = i * TAU / PHI;
     final r = sqrt(i) * SCALE_FACTOR;
     final x = centerX + r * cos(theta);
     final y = centerY - r * sin(theta);
     new SunflowerSeed(x, y, SEED_RADIUS).draw(context);
   }
-  notes.textContent = "$seeds seeds";
+  notes.text = "$seeds seeds";
 }
 
 // This example was modified to use classes and mixins.
 class SunflowerSeed extends Circle with CirclePainter {
   SunflowerSeed(num x, num y, num radius, [String color])
   : super(x, y, radius) {
     if (color != null) this.color = color;
   }
 }
-
-