Fix #9843. IScriptSnapshot can return undefined
Fix #9843. IScriptSnapshot can return undefined

vilic/TypeScript,minestarks/TypeScript,jeremyepling/TypeScript,DLehenbauer/TypeScript,erikmcc/TypeScript,weswigham/TypeScript,kpreisser/TypeScript,RyanCavanaugh/TypeScript,chuckjaz/TypeScript,RyanCavanaugh/TypeScript,mihailik/TypeScript,Microsoft/TypeScript,alexeagle/TypeScript,vilic/TypeScript,SaschaNaz/TypeScript,weswigham/TypeScript,TukekeSoft/TypeScript,chuckjaz/TypeScript,microsoft/TypeScript,jeremyepling/TypeScript,Eyas/TypeScript,microsoft/TypeScript,DLehenbauer/TypeScript,kpreisser/TypeScript,Microsoft/TypeScript,mihailik/TypeScript,kitsonk/TypeScript,thr0w/Thr0wScript,synaptek/TypeScript,DLehenbauer/TypeScript,Microsoft/TypeScript,donaldpipowitch/TypeScript,synaptek/TypeScript,kpreisser/TypeScript,synaptek/TypeScript,erikmcc/TypeScript,donaldpipowitch/TypeScript,alexeagle/TypeScript,RyanCavanaugh/TypeScript,SaschaNaz/TypeScript,basarat/TypeScript,jwbay/TypeScript,SaschaNaz/TypeScript,basarat/TypeScript,nojvek/TypeScript,basarat/TypeScript,vilic/TypeScript,basarat/TypeScript,donaldpipowitch/TypeScript,alexeagle/TypeScript,Eyas/TypeScript,thr0w/Thr0wScript,TukekeSoft/TypeScript,jeremyepling/TypeScript,nojvek/TypeScript,vilic/TypeScript,thr0w/Thr0wScript,DLehenbauer/TypeScript,jwbay/TypeScript,SaschaNaz/TypeScript,Eyas/TypeScript,TukekeSoft/TypeScript,minestarks/TypeScript,kitsonk/TypeScript,thr0w/Thr0wScript,chuckjaz/TypeScript,mihailik/TypeScript,mihailik/TypeScript,nojvek/TypeScript,jwbay/TypeScript,weswigham/TypeScript,jwbay/TypeScript,chuckjaz/TypeScript,erikmcc/TypeScript,minestarks/TypeScript,nojvek/TypeScript,erikmcc/TypeScript,microsoft/TypeScript,synaptek/TypeScript,donaldpipowitch/TypeScript,kitsonk/TypeScript,Eyas/TypeScript