Implement newly proposed DOM selection approach

[jcmoore]

There may be some possible improvements for selecting light-DOM nodes in a shadow-rooted element with no contained content element -- I also tried querying the whole DOM natively and traversing it instead of the wrapped tree (https://gist.github.com/jcmoore/69a49f887e03c1d2bfa1#file-queryselector2-js) but it was no faster than the original method, and probably had significant memory implications.

[jcmoore]

Polymer/polymer#629

[arv]

keep this as wrapIfNeeded to avoid confusion

[ebidel]

Before this PR can be merged, please sign the CLA. See the CONTRIBUTING guide.

[jcmoore]

I'd already received confirmation that the MediaMath's (corporate) CLA had been accepted ([email protected]), do I need to send a copy somewhere else?

[ebidel]

Got it. Thanks for the heads up.

[ebidel]

Thanks for signing the CLA!

[arv]

How about?

// When we get a ShadowRoot the logical tree is going to be disconnected so we do a manual tree traversal

Any reason this is not just the else branch?

if (target instanceof OriginalElement)
  list = originalElementQuerySelectorAll.call(target, selector);
else if (target instanceof OriginalDocument)
  list = originalDocumentQuerySelectorAll.call(target, selector);
else
  return findElements(this, index, result, p, selector, null);

[arv]

LGTM once you fix the curlies for the if/else. (You can use curlies for all if/else if you want too).

Can you squash these into a single commit?

We usually include "Fixes #N" in the commit message too.

[jcmoore]

Ah, to do a squash on the commits do I need a new pull-request (on a new branch?

(I'm unfamiliar with the process I'm afraid)

[arv]

No need for a new PR or a new branch:

http://blog.steveklabnik.com/posts/2012-11-08-how-to-squash-commits-in-a-github-pull-request

[jcmoore]

All squashed

[arv]

Thank you so much. Lets hope this one does not cause any real world issues.

@sjmiles @sorvell Keep your eyes open.

[sjmiles]

Thanks you guys. :) We'll check it out.

[frankiefu]

Filed an issue seems to be related to this change. https://github.com/Polymer/ShadowDOM/issues/476

[jcmoore]

(Very new to pull-request work-flow). In order to address this, must I do a brand new pull-request?

[arv]

Yeah. A new pull request seems appropriate.