This reverts commit 9ceaf212.

Reason for revert: Fails on arm: http://build.chromium.org/p/client.v8.ports/builders/V8%20Arm%20-%20debug/builds/2950/steps/Check/logs/Bits.RoundUpToPowerOf..

Original change's description:
> [base] Introduce RoundUpToPowerOfTwo64
> 
> And fix RoundUpToPowerOfTwo32 to return 1 for the input 0.
> 0 is no power of two.
> Beside being the correct value, this also avoids a special case in the
> (new) fast path using the number of leading zeros.
> 
> R=​jochen@chromium.org, ahaas@chromium.org
> 
> Change-Id: I87173495e13b334954bcebbb55724fb666dfa809
> Reviewed-on: https://chromium-review.googlesource.com/488143
> Reviewed-by: Jochen Eisinger <jochen@chromium.org>
> Reviewed-by: Andreas Haas <ahaas@chromium.org>
> Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#44925}

TBR=ahaas@chromium.org,jochen@chromium.org,clemensh@chromium.org,v8-reviews@googlegroups.com,wasm-v8@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: Ib353ee0a944316da6f919bac3bb88d4f95d98ea0
Reviewed-on: https://chromium-review.googlesource.com/488365Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44935}