Internal: b/154410718

For desktop platforms (including Web), it makes sense to exclude disabled controls from directional focus.

However, if directional keys are your main form of input, this leads to confusing situations. For example, if a button gets disabled when you activate it, focus will jump to a different control.

Having a parameter to allow focusable controls to maintain focus while in a disabled state would solve this.

cc @gspencergoog @HansMuller