Page scrolling does not work

[akosyakov]

Steps to reproduce:

1. go to https://microsoft.github.io/monaco-editor/;
2. hover over the editor;
3. try to scroll the page down;
4. it is not possible.

It will be nice if after the scroll bar reached the bottom (or the top) of the editor then a page scroll bar is used.

[svenefftinge]

I think that would be the natural behavior if the event was propagated.
Compare e.g. with the scolling behavior here https://codemirror.net/demo/complete.html

[alexdima]

Dup of #69 which just got fixed.