Revert of enforce 16byte alignment in shader contexts (patchset #1 id:1 of https://codereview.chromium.org/1759653004/ )

Reason for revert:

Test-Win8-MSVC-ShuttleB-CPU-AVX2-x86-Debug failed dm:

	....
    FYI: loaded 23439 distinct uninteresting hashes from 23439 lines
    Skipping config gpu: Don't understand 'gpu'.
    Skipping config msaa16: Don't understand 'msaa16'.
    168400 srcs * 7 sinks + 481 tests == 1179281 tasks
    0ns elapsed, 5 active, 1179276 queued, 55MB RAM, 55MB peak
        565 gm  xfermodes2
        565 gm  xfermodes
        565 gm  xfermodeimagefilter
        565 gm  xfermodes3
        565 gm  verylarge_picture_image
    c:\0\build\slave\workdir\build\skia\src\core\skshader.cpp:108:
        fatal error: ""(0 == ((size) & 15))""
    step returned non-zero exit code: 3
    @@@STEP_FAILURE@@@

Original issue's description:
> enforce 16byte alignment in shader contexts
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1759653004
>
> Committed: https://skia.googlesource.com/skia/+/d812fb458807245daa812adb7af0733cf5b54d96

TBR=mtklein@google.com,fmalita@chromium.org,herb@google.com,reed@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/1759323002
30 files changed