sort classes in dependency order, or load lazily if needed, fixes #78

test/codegen/expect/sunflower.js

 var sunflower;
 (function(exports) {
   'use strict';
   let ORANGE = "orange";
   let SEED_RADIUS = 2;
   let SCALE_FACTOR = 4;
   let TAU = dart.notNull(math.PI) * 2;
   let MAX_D = 300;
   let centerX = dart.notNull(MAX_D) / 2;
   let centerY = centerX;
   // Function querySelector: (String) → Element
   function querySelector(selector) {
     return dom.document.querySelector(selector);
   }
   exports.seeds = 0;
   dart.defineLazyProperties(exports, {
     get slider() {
       return dart.as(querySelector("#slider"), dom.InputElement);
     },
     get notes() {
       return querySelector("#notes");
     },
     get PHI() {
       return (dart.notNull(math.sqrt(5)) + 1) / 2;
     },
     get context() {
       return dart.as(dart.as(querySelector("#canvas"), dom.CanvasElement).getContext('2d'), dom.CanvasRenderingContext2D);
     }
   });
+  // Function main: () → void
+  function main() {
+    exports.slider.addEventListener('change', (e) => draw());
+    draw();
+  }
+  // Function draw: () → void
+  function draw() {
+    exports.seeds = core.int.parse(exports.slider.value);
+    exports.context.clearRect(0, 0, MAX_D, MAX_D);
+    for (let i = 0; dart.notNull(i) < dart.notNull(exports.seeds); i = dart.notNull(i) + 1) {
+      let theta = dart.notNull(i) * dart.notNull(TAU) / dart.notNull(exports.PHI);
+      let r = dart.notNull(math.sqrt(i)) * dart.notNull(SCALE_FACTOR);
+      let x = dart.notNull(centerX) + dart.notNull(r) * dart.notNull(math.cos(theta));
+      let y = dart.notNull(centerY) - dart.notNull(r) * dart.notNull(math.sin(theta));
+      new SunflowerSeed(x, y, SEED_RADIUS).draw();
+    }
+    exports.notes.textContent = `${exports.seeds} seeds`;
+  }
   class Circle extends core.Object {
     Circle(x, y, radius) {
       this.x = x;
       this.y = y;
       this.radius = radius;
     }
   }
   class CirclePainter extends core.Object {
     CirclePainter() {
       this.color = ORANGE;
@@ skipping 11 matching lines @@
   }
   class SunflowerSeed extends dart.mixin(Circle, CirclePainter) {
     SunflowerSeed(x, y, radius, color) {
       if (color === void 0)
         color = null;
       super.Circle(x, y, radius);
       if (color !== null)
         this.color = color;
     }
   }
-  // Function main: () → void
-  function main() {
-    exports.slider.addEventListener('change', (e) => draw());
-    draw();
-  }
-  // Function draw: () → void
-  function draw() {
-    exports.seeds = core.int.parse(exports.slider.value);
-    exports.context.clearRect(0, 0, MAX_D, MAX_D);
-    for (let i = 0; dart.notNull(i) < dart.notNull(exports.seeds); i = dart.notNull(i) + 1) {
-      let theta = dart.notNull(i) * dart.notNull(TAU) / dart.notNull(exports.PHI);
-      let r = dart.notNull(math.sqrt(i)) * dart.notNull(SCALE_FACTOR);
-      let x = dart.notNull(centerX) + dart.notNull(r) * dart.notNull(math.cos(theta));
-      let y = dart.notNull(centerY) - dart.notNull(r) * dart.notNull(math.sin(theta));
-      new SunflowerSeed(x, y, SEED_RADIUS).draw();
-    }
-    exports.notes.textContent = `${exports.seeds} seeds`;
-  }
   // Exports:
   exports.ORANGE = ORANGE;
   exports.SEED_RADIUS = SEED_RADIUS;
   exports.SCALE_FACTOR = SCALE_FACTOR;
   exports.TAU = TAU;
   exports.MAX_D = MAX_D;
   exports.centerX = centerX;
   exports.centerY = centerY;
   exports.querySelector = querySelector;
+  exports.main = main;
+  exports.draw = draw;
+  exports.SunflowerSeed = SunflowerSeed;
   exports.Circle = Circle;
   exports.CirclePainter = CirclePainter;
-  exports.SunflowerSeed = SunflowerSeed;
-  exports.main = main;
-  exports.draw = draw;
 })(sunflower || (sunflower = {}));