Remove the basic Math.sumPrecise polyfill

[Snuffleupagus]

This is already polyfilled properly via core-js in legacy builds, and the only reason that it wasn't already removed is that the tests (on the bots) use the "modern" builds and Chrome didn't support Math.sumPrecise until now; see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/sumPrecise#browser_compatibility

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.51%. Comparing base (2643125) to head (8ac7305).

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #20958   +/-   ##
=======================================
  Coverage   62.51%   62.51%           
=======================================
  Files         172      172           
  Lines      121789   121776   -13     
=======================================
- Hits        76134    76132    -2     
+ Misses      45655    45644   -11     

Flag	Coverage Δ
fonttest	7.65% <ø> (?)
unittestcli	62.49% <ø> (-0.03%)	⬇️

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