New toggle-attribute command.

[bob2517]

This is a quick one for the core, so I'm adding this in for 2.10.0. Just need to write up the docs for it.

Follows spec: https://developer.mozilla.org/en-US/docs/Web/API/Element/toggleAttribute

ACSS syntax:

button:click {
  input {
    toggle-attribute: disabled;
  }
}

Equivalent JS Syntax (without including code for additional ACSS features such as event persistence):

var button = document.querySelector("button");
var input = document.querySelector("input");

if (button && input) {
  button.addEventListener("click", function() {
    input.toggleAttribute("disabled");
  }
});

[bob2517]

Includes the optional force option per the JS spec.

[bob2517]

Now on the 2.10.0 branch.