indent_style=space doesn't give warning when a single line uses tab

[SimenB]

Discovered in airbnb/javascript#1102, using editorconfig-tools check.

It seems like the check doesn't go through all lines. If I use indent_style=space, a single tab goes unnoticed, but if all lines are using tabs, I get yelled at. It's the same the other way around; having indent_style=tab, a single line using spaces for indentation goes unnoticed, but if the whole file is indented with spaces, it fails.