fixes #52, fields shadowing getters/setters or other fields

test/codegen/expect/sunflower/dom.js

 var dom;
 (function(exports) {
   'use strict';
+  let name$ = Symbol('name');
   class JsName extends core.Object {
+    get name() {
+      return this[name$];
+    }
     JsName(opts) {
       let name = opts && 'name' in opts ? opts.name : null;
-      this.name = name;
+      this[name$] = name;
     }
   }
   class Overload extends core.Object {
     Overload() {
     }
   }
   let overload = new Overload();
   let EventListener = dart.typedef('EventListener', () => dart.functionType(dart.void, [Event]));
   class Event extends core.Object {}
   let InputElement = HTMLInputElement;
   let CanvasElement = HTMLCanvasElement;
   class RenderingContext extends core.Object {}
+  let lineWidth = Symbol('lineWidth');
+  let lineCap = Symbol('lineCap');
+  let lineJoin = Symbol('lineJoin');
+  let miterLimit = Symbol('miterLimit');
+  let lineDashOffset = Symbol('lineDashOffset');
+  let font = Symbol('font');
+  let textAlign = Symbol('textAlign');
+  let textBaseline = Symbol('textBaseline');
   class CanvasDrawingStyles extends core.Object {
     CanvasDrawingStyles() {
-      this.lineWidth = null;
-      this.lineCap = null;
-      this.lineJoin = null;
-      this.miterLimit = null;
-      this.lineDashOffset = null;
-      this.font = null;
-      this.textAlign = null;
-      this.textBaseline = null;
+      this[lineWidth] = null;
+      this[lineCap] = null;
+      this[lineJoin] = null;
+      this[miterLimit] = null;
+      this[lineDashOffset] = null;
+      this[font] = null;
+      this[textAlign] = null;
+      this[textBaseline] = null;
+    }
+    get lineWidth() {
+      return this[lineWidth];
+    }
+    set lineWidth(value) {
+      this[lineWidth] = value;
+    }
+    get lineCap() {
+      return this[lineCap];
+    }
+    set lineCap(value) {
+      this[lineCap] = value;
+    }
+    get lineJoin() {
+      return this[lineJoin];
+    }
+    set lineJoin(value) {
+      this[lineJoin] = value;
+    }
+    get miterLimit() {
+      return this[miterLimit];
+    }
+    set miterLimit(value) {
+      this[miterLimit] = value;
+    }
+    get lineDashOffset() {
+      return this[lineDashOffset];
+    }
+    set lineDashOffset(value) {
+      this[lineDashOffset] = value;
+    }
+    get font() {
+      return this[font];
+    }
+    set font(value) {
+      this[font] = value;
+    }
+    get textAlign() {
+      return this[textAlign];
+    }
+    set textAlign(value) {
+      this[textAlign] = value;
+    }
+    get textBaseline() {
+      return this[textBaseline];
+    }
+    set textBaseline(value) {
+      this[textBaseline] = value;
     }
   }
   class CanvasPathMethods extends core.Object {}
   // Exports:
   exports.JsName = JsName;
   exports.Overload = Overload;
   exports.overload = overload;
   exports.EventListener = EventListener;
   exports.Event = Event;
   exports.InputElement = InputElement;
   exports.CanvasElement = CanvasElement;
   exports.RenderingContext = RenderingContext;
   exports.CanvasDrawingStyles = CanvasDrawingStyles;
   exports.CanvasPathMethods = CanvasPathMethods;
 })(dom || (dom = window));