The rest of FixedBitVector's code relies on this relationship. So, let's make it explicit. Also, fixed a bug in BitMap's API tests: testBitmapConcurrentTestAndSet() and testBitmapConcurrentTestAndClear() were exercising testAndSet() and testAndClear() respectively instead of their concurrent versions. This was originally found by Yijia Huang in https://bugs.webkit.org/show_bug.cgi?id=250847.
<rdar://problem/104731974>
Pull request: https://github.com/WebKit/WebKit/pull/9211
Committed 259490@main (c2393f9a46af): <https://commits.webkit.org/259490@main> Reviewed commits have been landed. Closing PR #9211 and removing active labels.