Merge branch 'master' into referencesDogfood_1

src/compiler/program.ts

@@ -573,7 +573,6 @@ namespace ts {
         const packageIdToSourceFile = createMap<SourceFile>();
         // Maps from a SourceFile's `.path` to the name of the package it was imported with.
         let sourceFileToPackageName = createMap<string>();
-        // See `sourceFileIsRedirectedTo`.
         let redirectTargetsSet = createMap<true>();
 
         const filesByName = createMap<SourceFile | undefined>();