Remove keyCode support in v-on

[yyx990803]

• Drop support for using numbers (keyCodes) as v-on modifiers
• Remove config.keyCodes

KeyboardEvent.keyCode has been deprecated and we already have support for using KeyboardEvent.key as modifiers.

Rendered

[Meekohi]

(edit: sorry was looking at .code instead of .key)

Browser support for .key: https://caniuse.com/#feat=keyboardevent-key

[leopiccionia]

KeyboardEvent.key may often return values that aren't template-friendly, like ., =, >, etc. I can't imagine common cases where those would be handy, though. On the worst hypothesis, one can check the key inside event handler.

An exception would be the space bar ( ), that even gained a "named" modifier in 2.x (.space). Will "named" 2.x modifiers like this be kept? Some of them (.esc, the four arrows) have non-standard keys in IE11, according to MDN.

[yyx990803]

@leopiccionia yes, 2.x built-in aliases will be kept.

[yyx990803]

This RFC is now in final comments stage. An RFC in final comments stage means that:

The core team has reviewed the feedback and reached consensus about the general direction of the RFC and believe that this RFC is a worthwhile addition to the framework.
Final comments stage does not mean the RFC's design details are final - we may still tweak the details as we implement it and discover new technical insights or constraints. It may even be further adjusted based on user feedback after it lands in an alpha/beta release.
If no major objections with solid supporting arguments have been presented after a week, the RFC will be merged and become an active RFC.