Starts saturating CPU when functions with double backticks are used

[adam-becker]

The Hedgehog library has xunit tests that look like this:

[<Fact>]
let ``unicode doesn't return any surrogate`` () = // ...

When editing these files with ionide, I get very high CPU usage, and the editor itself eventually crashes. If I don't open files with double backticks in them, this doesn't happen.