lib: prefer symbol to number in webidl type function

[aduh95]

It seems to be more suited.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.40%. Comparing base (e53fe03) to head (7403a7a).
Report is 8 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #55737   +/-   ##
=======================================
  Coverage   88.39%   88.40%           
=======================================
  Files         654      654           
  Lines      187728   187729    +1     
  Branches    36117    36118    +1     
=======================================
+ Hits       165948   165956    +8     
+ Misses      15015    15007    -8     
- Partials     6765     6766    +1     

Files with missing lines	Coverage Δ
lib/internal/webidl.js	93.18% <100.00%> (+0.01%)	⬆️

... and 16 files with indirect coverage changes

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/63443/