Tag closures with their types

test/codegen/expect/sunflower/sunflower.js

 var sunflower = dart.defineLibrary(sunflower, {});
 var math = dart.import(math);
 var dom = dart.import(dom);
 var core = dart.import(core);
 (function(exports, math, dom, core) {
   '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);
   }
+  dart.fn(querySelector, dom.Element, [core.String]);
   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());
+    exports.slider.addEventListener('change', dart.fn(e => draw(), dart.void, [dart.dynamic]));
     draw();
   }
-  // Function draw: () → void
+  dart.fn(main, dart.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`;
   }
+  dart.fn(draw, dart.void, []);
   class Circle extends core.Object {
     Circle(x, y, radius) {
       this.x = x;
       this.y = y;
       this.radius = radius;
     }
   }
+  dart.setSignature(Circle, {});
   class CirclePainter extends core.Object {
     CirclePainter() {
       this.color = ORANGE;
     }
     draw() {
       exports.context.beginPath();
       exports.context.lineWidth = 2;
       exports.context.fillStyle = this.color;
       exports.context.strokeStyle = this.color;
       exports.context.arc(this.x, this.y, this.radius, 0, TAU, false);
       exports.context.fill();
       exports.context.closePath();
       exports.context.stroke();
     }
   }
   CirclePainter[dart.implements] = () => [Circle];
+  dart.setSignature(CirclePainter, {
+    methods: () => ({draw: dart.functionType(dart.void, [])})
+  });
   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;
     }
   }
+  dart.setSignature(SunflowerSeed, {});
   // 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.Circle = Circle;
   exports.CirclePainter = CirclePainter;
   exports.SunflowerSeed = SunflowerSeed;
 })(sunflower, math, dom, core);