* Remove last trailing line for directives-only files
There are two hardlines that are added that do not need to.
- The first one is when there's an empty line afterwards, we want to remove it. The solution I opted for to fix this one is to trimRight the originalText so that globally it's never going to return yes for the isNextLineEmpty.
- The second one is at the end of Program, but we already printed it inside of the directive itself, so we can just add a condition to make sure it's only printed when there's a body or a comment, but not a directive.
Fixes#527
* Add comment
* Add parentheses if node is StringLiteral surrounded by ExpressionStatement :tools:.
* Add new test.
* Update tests to run against Babylon, plus no regression case.
* Split actual test and no regression test in two files.
* Disable Flow till facebook/flow#3234 is merged.
Rogelio Guzman