Auto merge of #2857 - avborhanian:master, r=phansch

Auto merge of #2857 - avborhanian:master, r=phansch

Adding lint test for excessive LOC.

This is a WIP for #2377. Just wanted to pull in because I had a few questions:

1. Is it okay that I'm approaching this via counting by looking at each line in the snippet instead of looking at the AST tree? If there's another way to do it, I want to make sure I'm doing the correct way, but I wasn't sure since the output AST JSON doesn't seem to contain whitespace.

2. My function is definitely going to trigger the lint, so also wanted to see if there was something obvious I could do to reduce it.

3. Are the two tests fine, or is there something obvious I'm missing?

4. Obviously bigger question - am I approaching the line count correctly. Current strategy is count a line if it contains some code, so skip if it's just comments or empty.