nl_tokens: This function is used to propagate certain flags when creating new object type references and union types . It is only necessary to do so if a constituent type might be the undefined type the null type the type of an object literal or the anyFunctionType . This is because there are operations in the type checker that care about the presence of such types at arbitrary depth in a containing type .
pl_tokens: function getPropagatingFlagsOfTypes ( types ) { var result = 0 ; for ( var _i = 0 ; _i < types . length ; _i ++ ) { var type = types [ _i ] ; result |= type . <mask> ; } return result & 14680064 /* PropagatingFlags */ ; }