Add a visual pulse to current line when user tries to go to a definition they're already at

Created by: quinnkeast

Problem Statement

When users click "Go to definition" while already at that definition, there's no feedback in response to their action, which can lead to a "mental hiccup" at the lack of response. If we improve this, it'll improve usability of "Go to definition" by reinforcing the user is already at the definition.

Solution

When the user clicks "Go to definition" when they're already at that definition, pulse the background colour of the current line. Quick example (for demo purposes, not exactly how it would look):

I don't think we'll be able to measure the impact of this, but it's a usability paper cut we ought fix!