Revert of VectorICs: megamorphic keyed loads in crankshaft don't need a vector. (patchset #3 id:40001 of https://codereview.chromium.org/1067573003/)

Reason for revert:
[Sheriff] Speculative revert for windows failure... will reland if it doesn't help:
http://build.chromium.org/p/client.v8/builders/V8%20Win32%20-%20debug%20-%202/builds/2891

Original issue's description:
> VectorICs: megamorphic keyed loads in crankshaft don't need a vector.
>
> They are content with a dummy vector, as MISSES won't result in
> changing the real vector/slot at all.
>
> BUG=
>
> Committed: https://crrev.com/c8e4d57d3b3036a05902f5b916cb5d853a57393c
> Cr-Commit-Position: refs/heads/master@{#27788}

TBR=dcarney@chromium.org,mvstanton@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1060263003

Cr-Commit-Position: refs/heads/master@{#27790}