Revert of Use SkMScalar as intermediates in SkMatrix44::setConcat. (https://coderevie...

Revert of Use SkMScalar as intermediates in SkMatrix44::setConcat. (https://codereview.chromium.org/146823002/)

Reason for revert:
This will break many Chromium tests when we roll.

Original issue's description:
> Use SkMScalar as intermediates in SkMatrix44::setConcat.
>
> BUG=skia:
>
> Committed: http://code.google.com/p/skia/source/detail?r=13167

R=reed@google.com
TBR=reed@google.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Author: mtklein@google.com

Review URL: https://codereview.chromium.org/147033002

git-svn-id: http://skia.googlecode.com/svn/trunk@13173 2bbb7eff-a529-9590-31e7-b0007b416f81