Use Object.defineProperty instead direct define when create polyfilled HTMLCollection

[louielin]

Direct define would cause enumerable issue. This behavior may break some js lib.

Object.keys(document.querySelectorAll('body'));
// 0, item, namedItem

var buttons = document.querySelectorAll('button');
Object.keys(buttons).forEach(function(i) {
    var button = buttons[i];
    button.addEventListener(/*...*/); // raise error when "i" is "item" or "namedItem"
);

Using Object.defineProperty and ensure enumerable equal to false will let "item" and "namedItem" methods disappear in Object.keys and for loop

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[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

:memo: Please visit https://cla.developers.google.com/ to sign.

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Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
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[louielin]

@googlebot I signed it!

@googlebot I signed it!

[googlebot]

CLAs look good, thanks!

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[googlebot]

CLAs look good, thanks!

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[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.