[MERGE #4556 @MikeHolman] disable timing out test on osx
[MERGE #4556 @MikeHolman] disable timing out test on osx

Merge pull request #4556 from MikeHolman:disableslowosx

It's a slow test in general and the OSX machines are very slow so this is timing out.

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