partially implement instance of checks and some codegen fixes

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) {
@@ skipping 19 matching lines @@
       }
       ['=='](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() {
         return _JenkinsSmiHash.hash2(this.x.hashCode, this.y.hashCode);
       }
       ['+'](other) {
-        return new Point(dart.as(this.x['+'](other.x), T), dart.as(this.y['+'](other.y), T));
+        return new (Point$(T))(dart.as(this.x['+'](other.x), T), dart.as(this.y['+'](other.y), T));
       }
       ['-'](other) {
-        return new Point(dart.as(this.x['-'](other.x), T), dart.as(this.y['-'](other.y), T));
+        return new (Point$(T))(dart.as(this.x['-'](other.x), T), dart.as(this.y['-'](other.y), T));
       }
       ['*'](factor) {
-        return new Point(dart.as(this.x['*'](factor), T), dart.as(this.y['*'](factor), T));
+        return new (Point$(T))(dart.as(this.x['*'](factor), T), dart.as(this.y['*'](factor), T));
       }
       get magnitude() {
         return sqrt(dart.notNull(this.x['*'](this.x)) + dart.notNull(this.y['*'](this.y)));
       }
       distanceTo(other) {
         let dx = this.x['-'](other.x);
         let dy = this.y['-'](other.y);
         return sqrt(dart.notNull(dx) * dart.notNull(dx) + dart.notNull(dy) * dart.notNull(dy));
       }
       squaredDistanceTo(other) {
@@ skipping 33 matching lines @@
       get hashCode() {
         return _JenkinsSmiHash.hash4(this.left.hashCode, this.top.hashCode, this.right.hashCode, this.bottom.hashCode);
       }
       intersection(other) {
         let x0 = max(this.left, other.left);
         let x1 = min(this.left['+'](this.width), other.left['+'](other.width));
         if (dart.notNull(x0) <= dart.notNull(x1)) {
           let y0 = max(this.top, other.top);
           let y1 = min(this.top['+'](this.height), other.top['+'](other.height));
           if (dart.notNull(y0) <= dart.notNull(y1)) {
-            return new Rectangle(dart.as(x0, T), dart.as(y0, T), dart.as(dart.notNull(x1) - dart.notNull(x0), T), dart.as(dart.notNull(y1) - dart.notNull(y0), T));
+            return new (Rectangle$(T))(dart.as(x0, T), dart.as(y0, T), dart.as(dart.notNull(x1) - dart.notNull(x0), T), dart.as(dart.notNull(y1) - dart.notNull(y0), T));
           }
         }
         return null;
       }
       intersects(other) {
         return dart.notNull(this.left['<='](dart.notNull(other.left) + dart.notNull(other.width))) && dart.notNull(other.left) <= dart.notNull(this.left['+'](this.width)) && dart.notNull(this.top['<='](dart.notNull(other.top) + dart.notNull(other.height))) && dart.notNull(other.top) <= dart.notNull(this.top['+'](this.height));
       }
       boundingBox(other) {
         let right = max(this.left['+'](this.width), other.left['+'](other.width));
         let bottom = max(this.top['+'](this.height), other.top['+'](other.height));
         let left = min(this.left, other.left);
         let top = min(this.top, other.top);
-        return new Rectangle(dart.as(left, T), dart.as(top, T), dart.as(dart.notNull(right) - dart.notNull(left), T), dart.as(dart.notNull(bottom) - dart.notNull(top), T));
+        return new (Rectangle$(T))(dart.as(left, T), dart.as(top, T), dart.as(dart.notNull(right) - dart.notNull(left), T), dart.as(dart.notNull(bottom) - dart.notNull(top), T));
       }
       containsRectangle(another) {
         return dart.notNull(this.left['<='](another.left)) && dart.notNull(this.left['+'](this.width)) >= dart.notNull(another.left) + dart.notNull(another.width) && dart.notNull(this.top['<='](another.top)) && dart.notNull(this.top['+'](this.height)) >= dart.notNull(another.top) + dart.notNull(another.height);
       }
       containsPoint(another) {
         return core.num['>='](another.x, this.left) && dart.notNull(another.x) <= dart.notNull(this.left['+'](this.width)) && core.num['>='](another.y, this.top) && dart.notNull(another.y) <= dart.notNull(this.top['+'](this.height));
       }
       get topLeft() {
-        return new Point(this.left, this.top);
+        return new (Point$(T))(this.left, this.top);
       }
       get topRight() {
-        return new Point(dart.as(this.left['+'](this.width), T), this.top);
+        return new (Point$(T))(dart.as(this.left['+'](this.width), T), this.top);
       }
       get bottomRight() {
-        return new Point(dart.as(this.left['+'](this.width), T), dart.as(this.top['+'](this.height), T));
+        return new (Point$(T))(dart.as(this.left['+'](this.width), T), dart.as(this.top['+'](this.height), T));
       }
       get bottomLeft() {
-        return new Point(this.left, dart.as(this.top['+'](this.height), T));
+        return new (Point$(T))(this.left, dart.as(this.top['+'](this.height), T));
       }
     }
     return _RectangleBase;
   });
   let _RectangleBase = _RectangleBase$(dart.dynamic);
   let Rectangle$ = dart.generic(function(T) {
     class Rectangle extends _RectangleBase$(T) {
       Rectangle(left, top, width, height) {
         this.left = left;
         this.top = top;
         this.width = dart.as(width['<'](0) ? dart.notNull(width['unary-']()) * 0 : width, T);
         this.height = dart.as(height['<'](0) ? dart.notNull(height['unary-']()) * 0 : height, T);
         super._RectangleBase();
       }
       fromPoints(a, b) {
         let left = dart.as(min(a.x, b.x), T);
         let width = dart.as(core.num['-'](max(a.x, b.x), left), T);
         let top = dart.as(min(a.y, b.y), T);
         let height = dart.as(core.num['-'](max(a.y, b.y), top), T);
-        return new Rectangle(left, top, width, height);
+        return new (Rectangle$(T))(left, top, width, height);
       }
     }
     dart.defineNamedConstructor(Rectangle, 'fromPoints');
     return Rectangle;
   });
   let Rectangle = Rectangle$(dart.dynamic);
   let _width = Symbol('_width');
   let _height = Symbol('_height');
   let MutableRectangle$ = dart.generic(function(T) {
     class MutableRectangle extends _RectangleBase$(T) {
       MutableRectangle(left, top, width, height) {
         this.left = left;
         this.top = top;
         this[_width] = dart.as(width['<'](0) ? _clampToZero(width) : width, T);
         this[_height] = dart.as(height['<'](0) ? _clampToZero(height) : height, T);
         super._RectangleBase();
       }
       fromPoints(a, b) {
         let left = dart.as(min(a.x, b.x), T);
         let width = dart.as(core.num['-'](max(a.x, b.x), left), T);
         let top = dart.as(min(a.y, b.y), T);
         let height = dart.as(core.num['-'](max(a.y, b.y), top), T);
-        return new MutableRectangle(left, top, width, height);
+        return new (MutableRectangle$(T))(left, top, width, height);
       }
       get width() {
         return this[_width];
       }
       set width(width) {
         if (width['<'](0))
           width = dart.as(_clampToZero(width), T);
         this[_width] = width;
       }
       get height() {
@@ skipping 264 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 = {}));