Reason for revert:
problems on Mac64
Original issue's description:
> [turbofan] Add the StackSlot operator to turbofan.
>
> The StackSlot operator allows to allocate a spill slot on the stack. We
> are going to use this operator to pass floats through pointers to c
> functions, which we need for floating point rounding in the case where
> the architecture does not provide rounding instructions.
>
> R=titzer@chromium.org, v8-arm-ports@googlegroups.com, v8-ppc-ports@googlegroups.com, v8-mips-ports@googlegroups.com
>
> Committed: https://crrev.com/7a693437787090d62d937b862e29521debcc5223
> Cr-Commit-Position: refs/heads/master@{#33600}
TBR=titzer@chromium.org,v8-arm-ports@googlegroups.com,v8-mips-ports@googlegroups.com,v8-ppc-ports@googlegroups.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review URL: https://codereview.chromium.org/1644283002
Cr-Commit-Position: refs/heads/master@{#33601}
11f7c2e63c