Revert "Simplify BitVector code"

This reverts commit 82f0e3d3ea6bf927e3397b2fb423abbc5821a30f.

The change breaks the asan buildbots.

https://lab.llvm.org/buildbot/#/builders/99/builds/2835

GitOrigin-RevId: 8f9477b067b0e059ece95bae3e2bd84f95702666
1 file changed