This reverts commit d024b9a1.

Reason for revert: Left-over static counter in the code.

Original change's description:
> [regalloc] Introduce LiveRangeBundles
> 
> The idea behind this change is to restore some information about
> pre-ssa values to aid register allocation in sharing spill slots and
> reusing registers for connected live ranges.
> 
> By itself, this change does not improve much but it allows upcoming
> changes to freely spill and reload ranges without worrying about
> keeping the assignment stable.
> 
> Change-Id: I9320522592546655cc8fd0236d45fe075276a49e
> Reviewed-on: https://chromium-review.googlesource.com/c/1375665
> Commit-Queue: Stephan Herhut <herhut@chromium.org>
> Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#58688}

TBR=sigurds@chromium.org,herhut@chromium.org

Change-Id: Id4f84a0e418e17729a301c848a7b9694f0eb9931
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/1404439Reviewed-by: Stephan Herhut <herhut@chromium.org>
Commit-Queue: Stephan Herhut <herhut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58690}