Accept el.setAttribute('mixin', '')

[takahirox]

Description:

This PR enables el.setAttribute('mixin', '') (#2280).
It clears all mixins of el.

This PR doesn't touch removeAttribute('mixin') because
another guy is working on here #2282

[ngokevin]

Thanks!

[dmarcos]

can we check for el.mixinEls too? assert.equal(el.mixinEls.length, 2) before and assert.equal(el.mixinEls.length, 0) after

[takahirox]

That's a good idea. I will.

[dmarcos]

thanks!

[takahirox]

BTW, I'm thinking to replace new(old)Mixins.split(' ') with new(old)Mixins.trim().split(/\s+/).
The latter can accept two or more spaces, tabs, and new lines.
It'd be useful for users.

(example in the console)
-> var str = ' abc def\tghi\n jkl  mn  '
<- undefined
-> str
<- " abc def	ghi
     jkl  mn  "
-> str.split(' ')
<- ["", "abc", "def	ghi↵", "jkl", "", "mn", "", ""]
-> str.trim().split(/\s+/)
<- ["abc", "def", "ghi", "jkl", "mn"]

What do you guys think?

[dmarcos]

sure!