Speed up dropFunction by using a typed array instead of a sparse JS array.

[mstange]

This improves #4668 from 7.0 seconds to 1.6 seconds.

Before: https://share.firefox.dev/3qP8iB3
After: https://share.firefox.dev/43JVAC8

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.01 ⚠️

Comparison is base (ed4a724) 88.47% compared to head (197e034) 88.47%.

❗ Current head 197e034 differs from pull request most recent head f7ed6f4. Consider uploading reports for the commit f7ed6f4 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4670      +/-   ##
==========================================
- Coverage   88.47%   88.47%   -0.01%     
==========================================
  Files         295      295              
  Lines       26299    26290       -9     
  Branches     7099     7097       -2     
==========================================
- Hits        23269    23260       -9     
  Misses       2818     2818              
  Partials      212      212              

Impacted Files	Coverage Δ
src/profile-logic/transforms.js	91.42% <100.00%> (ø)

... and 6 files with indirect coverage changes

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[canova]

Noice! It's always great to see how a very small change can have a huge impact! :)

I guess this will increase the memory usage a bit (since we are initializing the whole array now), but it's a very small thing compared to the impact.