Angular throws an exception in the Console in checked mode for `cloneElements`

[chirayuk]

After commit dec8a97, Dartium (SDK 1.6.0-dev.any) logs the following stacktrace in the console.

type 'WhereIterable<Node>' is not a subtype of type 'Iterable<Element>' of 'function result'.

STACKTRACE:
#0      getElements (package:angular/core_dom/dom_util.dart:6:16)
#1      CssAnimate.insert (package:angular/animate/css_animate.dart:60:38)
#2      ViewPort.insert.<anonymous closure> (package:angular/core_dom/view.dart:49:22)
#3      RootScope.flush (package:angular/core/scope.dart:752:29)
#4      apply (package:angular/core/scope.dart:300:23)
#5      _rootRun (dart:async/zone.dart:835)
#6      _ZoneDelegate.run (dart:async/zone.dart:459)
#7      VmTurnZone._finishTurn (package:angular/core/zone.dart:157:21)
#8      VmTurnZone._onRunBase (package:angular/core/zone.dart:109:43)
#9      _onRun (package:angular/core/zone.dart:116:17)
#10     _CustomZone.run (dart:async/zone.dart:740)
#11     VmTurnZone.run (package:angular/core/zone.dart:244:40)
#12     Application.run (package:angular/application.dart:181:22)
#13     main (http://example.ngdart.localhost/animation.dart:33:11)