feat(dom): Add closest ponyfill

[kfranqueiro]

Fixes #3536.

I used td for unit tests since otherwise running them locally shows a huge gap (since Chrome supports native closest so the entire other branch never gets hit).

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@eadde7a). Click here to learn what that means.
The diff coverage is 100%.

@@           Coverage Diff            @@
##             master   #3559   +/-   ##
========================================
  Coverage          ?   98.4%           
========================================
  Files             ?     120           
  Lines             ?    5067           
  Branches          ?     629           
========================================
  Hits              ?    4986           
  Misses            ?      81           
  Partials          ?       0

Impacted Files	Coverage Δ
packages/mdc-dom/ponyfill.js	100% <100%> (ø)

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[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@eadde7a). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             master    #3559   +/-   ##
=========================================
  Coverage          ?   98.42%           
=========================================
  Files             ?      120           
  Lines             ?     5131           
  Branches          ?      636           
=========================================
  Hits              ?     5050           
  Misses            ?       81           
  Partials          ?        0

Impacted Files	Coverage Δ
packages/mdc-dom/ponyfill.js	100% <100%> (ø)

---

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Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@eadde7a). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             master    #3559   +/-   ##
=========================================
  Coverage          ?   98.42%           
=========================================
  Files             ?      120           
  Lines             ?     5131           
  Branches          ?      636           
=========================================
  Hits              ?     5050           
  Misses            ?       81           
  Partials          ?        0

Impacted Files	Coverage Δ
packages/mdc-dom/ponyfill.js	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update eadde7a...d0d7222. Read the comment docs.

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@eadde7a). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             master    #3559   +/-   ##
=========================================
  Coverage          ?   98.42%           
=========================================
  Files             ?      120           
  Lines             ?     5131           
  Branches          ?      636           
=========================================
  Hits              ?     5050           
  Misses            ?       81           
  Partials          ?        0

Impacted Files	Coverage Δ
packages/mdc-dom/ponyfill.js	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update eadde7a...d0d7222. Read the comment docs.