Consider having needsClick() check ancestry

[jimevans4000]

Observations:

• The needsClick() method returns true if the target is a label,
• Synthetic clicks apparently don't reliably toggle the label's associated checkbox (input of type checkbox), which I assume was the motivation for having this method return true for labels.

Problem:

• needsClick() returns false if the target is inside a label.
• Thus, if the user taps (say) a nested span inside the label, needsClick() returns false, and the associated input of type checkbox doesn't get toggled.

Possible resolutions:

• Have this method check ancestry, and return true if the target is a label or inside one. (I suspect that "label" is not the only case in this method that needs this ancestry check, e.g. span within a disabled button.)
• If the ancestry check is considered a performance concern, consider updating the "needsclick case 1" section of the doc so users know to watch out for this case.

Workaround:

• Page author can put needsclick class on all DOM nodes inside the label's subtree, which can be verbose.

[moodysalem]

+1 needsclick in a parent node should apply to all children nodes