Reserved keyword coloring?

Would it be possible to get reserved word coloring on variables? It should match the color of the other reserved words, to make it more obvious that the variable name cannot be used.

## Details

What editor are you seeing the problem in? **VS Code**

What version of the editor are you using? **1.22.2 and Insiders 1.23.0**

What color theme are you using? **Dark+ (default)**

## Repro

`var event = new Dictionary();`

Ends up formatted like this, with no obvious sign that `event` is a reserved word:

Instead of any reserved word errors, I kept seeing a bunch of (seemingly unrelated) errors in the vicinity of this line of code. I finally opened the project up in Visual Studio for macOS and it became obvious:

Riprodurre il problema in VS Code usando `var event = new Dictionary();` e confrontarlo con il comportamento mostrato di Visual Studio per macOS. Esaminare le regole di colorazione delle parole riservate della grammatica sintattica di C#; il lavoro è completato quando `event` viene colorato come le altre parole riservate senza alterare la sintassi circostante.

Scritto dal modello di indicizzazione a partire dal testo della issue.