Rationalize coercions

test/dart_codegen/expect/core/stopwatch.dart

 part of dart.core;
  class Stopwatch {int get frequency => _frequency;
  num _start;
  num _stop;
  Stopwatch() {
   _initTicker();
   }
  void start() {
   if (isRunning) return; if (_start == null) {
     _start = _now();
     }
    else {
     _start = _now() - (_stop - _start);
      _stop = null;
     }
   }
  void stop() {
   if (!isRunning) return; _stop = _now();
   }
  void reset() {
   if (_start == null) return; _start = _now();
    if (_stop != null) {
     _stop = _start;
     }
   }
  int get elapsedTicks {
   if (_start == null) {
     return 0;
     }
-   return ((__x11) => DEVC$RT.cast(__x11, num, int, "CastGeneral", """line 102, column 12 of dart:core/stopwatch.dart: """, __x11 is int, true))((_stop == null) ? (_now() - _start) : (_stop - _start));
+   return ((__x11) => DEVC$RT.cast(__x11, num, int, "ImplicitCast", """line 102, column 12 of dart:core/stopwatch.dart: """, __x11 is int, true))((_stop == null) ? (_now() - _start) : (_stop - _start));
   }
  Duration get elapsed {
   return new Duration(microseconds: elapsedMicroseconds);
   }
  int get elapsedMicroseconds {
   return (elapsedTicks * 1000000) ~/ frequency;
   }
  int get elapsedMilliseconds {
   return (elapsedTicks * 1000) ~/ frequency;
   }
  bool get isRunning => _start != null && _stop == null;
  static int _frequency;
  external static void _initTicker();
  external static int _now();
 }