[1.4>master] [MERGE #2122 @MikeHolman] skip ConstThis opt if this is non-enumerated library var (e.g. booleanTrue)
[1.4>master] [MERGE #2122 @MikeHolman] skip ConstThis opt if this is non-enumerated library var (e.g. booleanTrue)

Merge pull request #2122 from MikeHolman:constthislib

Microsoft/ChakraCore,Microsoft/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore