fix(list): make secondary items static

[devversion]

• The secondary items always had an absolute position, which causes issues with overflowing.
• This commit refactors the list to make the secondary items static.
• Fixes multiple secondary padding (as in specs - consistent)
• Fixes Proxy Scan for secondary items container
• Improved tests for the list component (more clear and more safe)

@crisbeto Maybe you can also review

Fixes #7500. Fixes #2759.

[crisbeto]

Why not wrap this as a jqLite element and use removeClass here?

[devversion]

There is no need, because, when iterating through a jqLite array, we retrieve always plain DOM elements.
So wrapping the element for one expression, is not needed in my opinion. In addition to that, it's just transferred this statement from the previous child block.

[crisbeto]

Sounds good, we should just bear in mind that classList can be a little inconsistent in IE. The way you're using it here should be fine though.

[devversion]

Just rechecked that code snippet, because you mentioned me on the IE10/9 issues with classList and figured out, that there's no need to remove that class anymore, because we are now always using a secondary container with static children. 👍

[crisbeto]

LGTM 👍

[EladBezalel]

LGTM, with that said, let this be one of the last PRs about list and focus on the new implementation,
@ThomasBurleson

[devversion]

I already wrote with Elad about the implementation, and I'm looking forward with helping to plan the new implementation.

Just want to summarize a few things here again:

• The secondary items are now static (this was a bug since many months)
  I compared the new secondary items with the old items and focused on the specs.
  That means, padding etc is all the same.
• The Proxy scan wasn't incorrect in the previous version. I've updated the scan logic here (no breaking change) and it works very well. (tested that with a lot user applications - codepens etc.)
• I've improved the tests, to be more clear
  That means, now the tests are more accurate and easier to read.
• Also RTL works very well on the list with the secondary items.

So I can say, I tested these things thoroughly, which I've listed before.

The only thing about I'am a bit unsure, is the flexFiller, which moves the secondary items to the end of the list.