Whitespace cleanup

Notes:

1. I haven't removed the trailing spaces in `test\css\media.css` since it results in tests failing
2. I haven't converted the tabs to spaces in `build.gradle` since I cannot test if it breaks that tool. If it doesn't let me know and I'll update the PR
3. I haven't removed the trailing spaces in dist since those are past releases

/CC @lukeapage: ping me when you want me to rebase the PR