Don't call dinvoke on Object methods

lib/runtime/dart/async.js

 var async;
 (function(exports) {
   'use strict';
   // Function _invokeErrorHandler: (Function, Object, StackTrace) → dynamic
   function _invokeErrorHandler(errorHandler, error, stackTrace) {
     if (dart.is(errorHandler, ZoneBinaryCallback)) {
       return dart.dinvokef(errorHandler, error, stackTrace);
     } else {
       return dart.dinvokef(errorHandler, error);
     }
   }
   // Function _registerErrorHandler: (Function, Zone) → Function
   function _registerErrorHandler(errorHandler, zone) {
     if (dart.is(errorHandler, ZoneBinaryCallback)) {
       return zone.registerBinaryCallback(errorHandler);
     } else {
       return zone.registerUnaryCallback(dart.as(errorHandler, dart.throw_("Unimplemented type (dynamic) → dynamic")));
     }
   }
   let _getBestStackTrace = Symbol('_getBestStackTrace');
   class AsyncError extends core.Object {
     AsyncError(error, stackTrace) {
       this.error = error;
       this.stackTrace = stackTrace;
     }
     toString() {
-      return dart.as(dart.dinvoke(this.error, 'toString'), core.String);
+      return this.error.toString();
     }
   }
   AsyncError[dart.implements] = () => [core.Error];
   class _UncaughtAsyncError extends AsyncError {
     _UncaughtAsyncError(error, stackTrace) {
       super.AsyncError(error, _UncaughtAsyncError[_getBestStackTrace](error, stackTrace));
     }
     static [_getBestStackTrace](error, stackTrace) {
       if (stackTrace != null)
         return stackTrace;
@@ skipping 5155 matching lines @@
   exports.ScheduleMicrotaskHandler = ScheduleMicrotaskHandler;
   exports.CreateTimerHandler = CreateTimerHandler;
   exports.CreatePeriodicTimerHandler = CreatePeriodicTimerHandler;
   exports.PrintHandler = PrintHandler;
   exports.ForkHandler = ForkHandler;
   exports.ZoneSpecification = ZoneSpecification;
   exports.ZoneDelegate = ZoneDelegate;
   exports.Zone = Zone;
   exports.runZoned = runZoned;
 })(async || (async = {}));