runtests.py: improve CRLF handling and popen working folder
runtests.py: improve CRLF handling and popen working folder

- Improve CRLF handling
- Set Javascript file path as a cwd for POpen to prevent the output/baseline path related differences

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