Alt-left does not go back

[samlh]

The left/right key handlers block the desired behavior of Alt-left/right to go forwards or backwards in the browser history.

Chrome Version 57.0.2987.133

Tested on https://doc.rust-lang.org/nightly/book/second-edition/ch15-01-box.html

[crazymerlyn]

This seems to have been fixed.

[budziq]

Hi,

this has been fixed a while ago in master.

cc @azerupi