keep mixin and interface implementation info at runtime

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 172 matching lines @@
       }
       get height() {
         return this[_height];
       }
       set height(height) {
         if (height['<'](0))
           height = dart.as(_clampToZero(height), T);
         this[_height] = height;
       }
     }
+    MutableRectangle[dart.implements] = [Rectangle$(T)];
     dart.defineNamedConstructor(MutableRectangle, 'fromPoints');
     return MutableRectangle;
   });
   let MutableRectangle = MutableRectangle$(dart.dynamic);
   // Function _clampToZero: (num) → num
   function _clampToZero(value) {
     dart.assert(dart.notNull(value) < 0);
     return -dart.notNull(value) * 0;
   }
   let E = 2.718281828459045;
@@ skipping 106 matching lines @@
       }
       return Math.random() * max >>> 0;
     }
     nextDouble() {
       return Math.random();
     }
     nextBool() {
       return Math.random() < 0.5;
     }
   }
+  _JSRandom[dart.implements] = [Random];
   let _lo = Symbol('_lo');
   let _hi = Symbol('_hi');
   let _MASK32 = Symbol('_MASK32');
   let _nextState = Symbol('_nextState');
   let _POW2_27_D = Symbol('_POW2_27_D');
   let _POW2_53_D = Symbol('_POW2_53_D');
   class _Random extends core.Object {
     _Random(seed) {
       this[_lo] = 0;
       this[_hi] = 0;
@@ skipping 84 matching lines @@
       let bits26 = dart.notNull(this[_lo]) & (1 << 26) - 1;
       this[_nextState]();
       let bits27 = dart.notNull(this[_lo]) & (1 << 27) - 1;
       return (dart.notNull(bits26) * dart.notNull(_Random[_POW2_27_D]) + dart.notNull(bits27)) / dart.notNull(_Random[_POW2_53_D]);
     }
     nextBool() {
       this[_nextState]();
       return (dart.notNull(this[_lo]) & 1) === 0;
     }
   }
+  _Random[dart.implements] = [Random];
   _Random._POW2_53_D = 1.0 * 9007199254740992;
   _Random._POW2_27_D = 1.0 * (1 << 27);
   _Random._MASK32 = 4294967295;
   // Exports:
   exports.Point = Point;
   exports.Point$ = Point$;
   exports.Random = Random;
   exports.Rectangle = Rectangle;
   exports.Rectangle$ = Rectangle$;
   exports.MutableRectangle = MutableRectangle;
@@ skipping 13 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 = {}));