Revert "Added dead variable / code elimination to skslc."

Revert "Added dead variable / code elimination to skslc."

This reverts commit 113628d76176a1ab3e6719c59efff23cd10ab213.

Reason for revert: Looks to have caused https://bugs.chromium.org/p/chromium/issues/detail?id=688939

Original change's description:
> Added dead variable / code elimination to skslc.
>
> BUG=skia:
>
> Change-Id: Ib037730803a8f222f099de0e001fe06ad452a22c
> Reviewed-on: https://skia-review.googlesource.com/7584
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
> Reviewed-by: Ben Wagner <benjaminwagner@google.com>
>

TBR=egdaniel@google.com,benjaminwagner@google.com,ethannicholas@google.com,reviews@skia.org
# Not skipping CQ checks because original CL landed > 1 day ago.
BUG=skia:

Change-Id: I85599e4ca2bc6bfd782edc163f67b64195d6ae65
Reviewed-on: https://skia-review.googlesource.com/8077
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>