Use unsigned type for `length` of JSFunction
Created attachment 407346 [details] Patch
Related ECMA-262 editorial PR: https://github.com/tc39/ecma262/pull/2153.
Committed r266210: <https://trac.webkit.org/changeset/266210> All reviewed patches have been landed. Closing bug and clearing flags on attachment 407346 [details].
<rdar://problem/67841309>