Simplified asyncValidator helper function
Simplified asyncValidator helper function

Author: Benjamin Strauß <benmastra@gmail.com>

Closes https://github.com/dart-lang/angular2/pull/57

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=132160920

chalin/angular2,chalin/angular2,matanlurey/angular,angulardart/angular,matanlurey/angular,kevmoo/angular,kevmoo/angular,angulardart/angular,kevmoo/angular,angulardart/angular,chalin/angular2,matanlurey/angular