Fix 'e.getModifierState is not a function' error for browser auto filled form events

[BusinessDuck]

Some browser events may not contains getMidifierState method. For example events, that produced by forms auto-fills.
Check the demo stand in associated issue #205214

Optional chaining for that method should solve the problem.

Test cases:

1. Autofill form by browser
2. Create event through the new Event() programmatically and dispatch, that will produce error also because correct way to use new KeyboardEvent()

[silverwind]

Any chance of a swift merge? The diff is trivial and this issue really affects Monaco users heavily.

@BusinessDuck can you change the PR title to something descriptive? It might be one reason why the PR was ignored so far.

[BusinessDuck]

Is that looks better now?

[silverwind]

Yes, thanks. The fix is good enough to get the error away.

The error also highlights a deeper underlying problem: VSCode should not be "listening in" on events that are targeting elements which are outside of its root element. Essentially, it's being a "bad neighbor" currently.

[alexdima]

Thank you!