Revert of Some inline ARM assembly for saturated arithmetic, a small speed-up for (https://codereview.chromium.org/346913004/)

Reason for revert:
Looks like this isn't compiling on android_clang_dbg (needed for the roll into chromium); reverting for now.

http://build.chromium.org/p/tryserver.chromium/builders/android_clang_dbg/builds/157031/steps/compile/logs/stdio

Original issue's description:
> Some inline ARM assembly for saturated arithmetic and a small speed-up
> for the C version of saturated add and subtract. Created a unit test for
> setting a saturated value.
> 
> Benchmarking using rasterize_and_record_micro.key_mobile_sites on a
> Nexus7 recorded a consistent drop in RasterizeAndRecordMicro:record_time
> from 5.18ms to 4.93ms (~5% improvement).
> 
> BUG=325746
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177208

TBR=bulach@chromium.org,skyostil@chromium.org,schenney@chromium.org,picksi@google.com,eseidel@chromium.org,eae@chromium.org,picksi@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=325746

Review URL: https://codereview.chromium.org/337323004

git-svn-id: svn://svn.chromium.org/blink/trunk@177212 bbb929c8-8fbe-4397-9dbb-9b2b20218538