Revert of Speedup stringsearch for two byte strings

Revert of Speedup stringsearch for two byte strings (patchset #3 id:40001 of https://codereview.chromium.org/1303033012/ )

Reason for revert:
[Sheriff] Breaks fuzzer and msan:
http://build.chromium.org/p/client.v8/builders/V8%20Fuzzer/builds/4773

Repro with:
tools/fuzz-harness.sh out/Debug/d8
(in a ninja Debug build)

Msan:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20arm64%20-%20sim%20-%20MSAN/builds/4097

Original issue's description:
> Speedup stringsearch for two byte strings
>
> Uses the lower byte with memchr which is
> significantly faster than a naive compare
>
> Performance difference with bench (http://hastebin.com/xuxexataso.js):
>
> old                             new
>
> single character                single character
> Κ found at 922                  Κ found at 922
> 3324                            616
> ㎡ found at 13217               ㎡ found at 13217
> 42366                           4931
> က found at 4096                 က found at 4096
> 13369                           9836
> ＀ found at 65280                ＀ found at 65280
> 207472                          36149
> ﾥ found at 65445                ﾥ found at 65445
> 209344                          36666
>   found at 8197                   found at 8197
> 26731                           11757
> 倂 found at 20482               倂 found at 20482
> 66071                           17193
>
> linear search                   linear search
> ΚΛ found at 922                 ΚΛ found at 922
> 4112                            504
> ㎡㎢ found at 13217             ㎡㎢ found at 13217
> 55105                           5119
> ﾥﾦ found at 65445               ﾥﾦ found at 65445
> 268016                          35496
>
> linear + bmh search             linear + bmh search
> ΚΛΜΝΞΟΠΡ found at 922           ΚΛΜΝΞΟΠΡ found at 922
> 2897                            522
> ﾥﾦﾧﾨﾩﾪﾫﾬ found at 65445         ﾥﾦﾧﾨﾩﾪﾫﾬ found at 65445
> 167687                          158465
>
> Committed: https://crrev.com/fced280f37588f8a232a414201276e053117e9ea
> Cr-Commit-Position: refs/heads/master@{#30587}

TBR=danno@chromium.org,mstarzinger@chromium.org,jkummerow@chromium.org,karl@skomski.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/df966cd287d92a4a984955a2cc8405f76dd5955a
Cr-Commit-Position: refs/heads/master@{#30588}

[Michael Achenbach, 2015-09-04 13:00:15]

Created Revert of Speedup stringsearch for two byte strings

[commit-bot: I haz the power, 2015-09-04 13:00:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1331433002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1331433002/1

[commit-bot: I haz the power, 2015-09-04 13:00:33]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-04 13:00:45]

Patchset 1 (id:??) landed as
https://crrev.com/df966cd287d92a4a984955a2cc8405f76dd5955a
Cr-Commit-Position: refs/heads/master@{#30588}

[Jakob Kummerow, 2015-09-04 13:12:28]

Ack, LGTM.

Karl, the workflow for relanding is:
(1) upload the original patch as a new codereview issue (either from a new local
git branch, or after "git cl issue 0" to reset the associated review), issue
description along the lines of: """
Reland 'Speedup string search for two byte strings'

With fixes for out-of-bounds vector access and the uninitialized memory access
reported by MSan.

Original review: https://codereview.chromium.org/1303033012/
"""

(2) fix the problem(s)
(3) upload the fixed version as a new patch set.
(4) get a review as usual (where the reviewer can just compare the two patch
sets, saving time)