fix: speed up getNodeFromTree

[paulirish]

axe.utils.getNodeFromTree currently doesn't return early if it has found a result. It continues iterating through the rest of the children. But the perf win is pretty huge: ~600ms on the page I'm testing.

To test I ran axe against this URL like this:

await window.axe.run(document, {performanceTimer:true, elementRef: true,runOnly: {  type: 'tag',  values: ['wcag2a', 'wcag2aa']},resultTypes: ['violations', 'inapplicable'],});

And then I looked at the Measure runchecks_color-contrast took XXXX ms line. (As that rule uses this method quite a lot).

numbers:

develop	this branch
3126	2351
3004	2399
2846	2360

On average, a 620ms improvement in this one rule.

Reviewer checks

Required fields, to be filled out by PR reviewer(s)

• Follows the commit message policy, appropriate for next version
• Has documentation updated, a DU ticket, or requires no documentation change
• Includes new tests, or was unnecessary
• Code is reviewed for security by: @WilcoFiers

[stephenmathieson]

nit: can remove this else since we return from the condition above.

[WilcoFiers]

Fantastic! Thanks for the contribution @paulirish!