Test for asyncIterator existance before defining
Test for asyncIterator existance before defining

donaldpipowitch/TypeScript,SaschaNaz/TypeScript,kitsonk/TypeScript,alexeagle/TypeScript,basarat/TypeScript,kpreisser/TypeScript,nojvek/TypeScript,SaschaNaz/TypeScript,basarat/TypeScript,microsoft/TypeScript,microsoft/TypeScript,basarat/TypeScript,Microsoft/TypeScript,RyanCavanaugh/TypeScript,RyanCavanaugh/TypeScript,nojvek/TypeScript,kpreisser/TypeScript,minestarks/TypeScript,weswigham/TypeScript,weswigham/TypeScript,alexeagle/TypeScript,alexeagle/TypeScript,basarat/TypeScript,nojvek/TypeScript,donaldpipowitch/TypeScript,kitsonk/TypeScript,RyanCavanaugh/TypeScript,kpreisser/TypeScript,SaschaNaz/TypeScript,SaschaNaz/TypeScript,microsoft/TypeScript,Microsoft/TypeScript,donaldpipowitch/TypeScript,minestarks/TypeScript,Microsoft/TypeScript,nojvek/TypeScript,kitsonk/TypeScript,weswigham/TypeScript,minestarks/TypeScript,donaldpipowitch/TypeScript