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

lib/runtime/dart/math.js

 var math;
 (function(exports) {
   'use strict';
   class _JenkinsSmiHash extends core.Object {
     static combine(hash, value) {
       hash = 536870911 & dart.notNull(hash) + dart.notNull(value);
       hash = 536870911 & dart.notNull(hash) + ((524287 & dart.notNull(hash)) << 10);
       return dart.notNull(hash) ^ dart.notNull(hash) >> 6;
     }
     static finish(hash) {
       hash = 536870911 & dart.notNull(hash) + ((67108863 & dart.notNull(hash)) << 3);
       hash = dart.notNull(hash) ^ dart.notNull(hash) >> 11;
       return 536870911 & dart.notNull(hash) + ((16383 & dart.notNull(hash)) << 15);
     }
     static hash2(a, b) {
       return _JenkinsSmiHash.finish(_JenkinsSmiHash.combine(_JenkinsSmiHash.combine(0, dart.as(a, core.int)), dart.as(b, core.int)));
     }
     static hash4(a, b, c, d) {
       return _JenkinsSmiHash.finish(_JenkinsSmiHash.combine(_JenkinsSmiHash.combine(_JenkinsSmiHash.combine(_JenkinsSmiHash.combine(0, dart.as(a, core.int)), dart.as(b, core.int)), dart.as(c, core.int)), dart.as(d, core.int)));
     }
   }
   let Point$ = dart.generic(function(T) {
     class Point extends core.Object {
       Point(x, y) {
-        this.x = x;
-        this.y = y;
+        dart.initField(Point, this, 'x', x);
+        dart.initField(Point, this, 'y', y);
       }
       toString() {
         return `Point(${this.x}, ${this.y})`;
       }
       ['=='](other) {
         if (!dart.is(other, Point))
           return false;
         return dart.notNull(dart.equals(this.x, dart.dload(other, 'x'))) && dart.notNull(dart.equals(this.y, dart.dload(other, 'y')));
       }
       get hashCode() {
@@ skipping 93 matching lines @@
       get bottomLeft() {
         return new (Point$(T))(this.left, dart.as(this.top['+'](this.height), T));
       }
     }
     return _RectangleBase;
   });
   let _RectangleBase = _RectangleBase$();
   let Rectangle$ = dart.generic(function(T) {
     class Rectangle extends _RectangleBase$(T) {
       Rectangle(left, top, width, height) {
-        this.left = left;
-        this.top = top;
-        this.width = dart.as(width['<'](0) ? dart.notNull(width['unary-']()) * 0 : width, T);
-        this.height = dart.as(height['<'](0) ? dart.notNull(height['unary-']()) * 0 : height, T);
+        dart.initField(Rectangle, this, 'left', left);
+        dart.initField(Rectangle, this, 'top', top);
+        dart.initField(Rectangle, this, 'width', dart.as(width['<'](0) ? dart.notNull(width['unary-']()) * 0 : width, T));
+        dart.initField(Rectangle, this, 'height', dart.as(height['<'](0) ? dart.notNull(height['unary-']()) * 0 : height, T));
         super._RectangleBase();
       }
       fromPoints(a, b) {
         let left = dart.as(min(a.x, b.x), T);
         let width = dart.as(core.num['-'](max(a.x, b.x), left), T);
         let top = dart.as(min(a.y, b.y), T);
         let height = dart.as(core.num['-'](max(a.y, b.y), top), T);
         return new (Rectangle$(T))(left, top, width, height);
       }
     }
     dart.defineNamedConstructor(Rectangle, 'fromPoints');
     return Rectangle;
   });
   let Rectangle = Rectangle$();
   let _width = Symbol('_width');
   let _height = Symbol('_height');
   let MutableRectangle$ = dart.generic(function(T) {
     class MutableRectangle extends _RectangleBase$(T) {
       MutableRectangle(left, top, width, height) {
-        this.left = left;
-        this.top = top;
+        dart.initField(MutableRectangle, this, 'left', left);
+        dart.initField(MutableRectangle, this, 'top', top);
         this[_width] = dart.as(width['<'](0) ? _clampToZero(width) : width, T);
         this[_height] = dart.as(height['<'](0) ? _clampToZero(height) : height, T);
         super._RectangleBase();
       }
       fromPoints(a, b) {
         let left = dart.as(min(a.x, b.x), T);
         let width = dart.as(core.num['-'](max(a.x, b.x), left), T);
         let top = dart.as(min(a.y, b.y), T);
         let height = dart.as(core.num['-'](max(a.y, b.y), top), T);
         return new (MutableRectangle$(T))(left, top, width, height);
@@ skipping 274 matching lines @@
   exports.sin = sin;
   exports.cos = cos;
   exports.tan = tan;
   exports.acos = acos;
   exports.asin = asin;
   exports.atan = atan;
   exports.sqrt = sqrt;
   exports.exp = exp;
   exports.log = log;
 })(math || (math = {}));