Revert "Use SkArenaAlloc instead of SkSmallAllocator in the SkAutoBlitterChoose code."

This reverts commit 2b57b7f7a7fc97db57f190b5a8ebcf68e177ee2d.

Reason for revert: Android compile failing

Original change's description:
> Use SkArenaAlloc instead of SkSmallAllocator in the SkAutoBlitterChoose code.
> 
> 
> TBR=reed@google.com
> Change-Id: Iefb044bf7657fbf982f23aa91a3f4d013ce2c626
> Reviewed-on: https://skia-review.googlesource.com/7786
> Reviewed-by: Mike Klein <mtklein@chromium.org>
> Reviewed-by: Herb Derby <herb@google.com>
> Commit-Queue: Herb Derby <herb@google.com>
> 

TBR=mtklein@chromium.org,mtklein@google.com,herb@google.com,reed@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: Id09c35377dddae0811d998b7d0c34c422325a5bc
Reviewed-on: https://skia-review.googlesource.com/8129
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/bench/SkLinearBitmapPipelineBench.cpp b/bench/SkLinearBitmapPipelineBench.cpp
index 0391798..4e892b6 100644
--- a/bench/SkLinearBitmapPipelineBench.cpp
+++ b/bench/SkLinearBitmapPipelineBench.cpp
@@ -7,8 +7,6 @@
 
 #include <memory>
 #include "Benchmark.h"
-
-#include "SkArenaAlloc.h"
 #include "SkBitmapProcShader.h"
 #include "SkColor.h"
 #include "SkArenaAlloc.h"
@@ -201,11 +199,12 @@
 
         SkAutoTMalloc<SkPMColor> buffer4b(width*height);
 
-        SkArenaAlloc alloc{kSkBlitterContextSize * sizeof(uint32_t)};
+        uint32_t storage[kSkBlitterContextSize];
         const SkShader::ContextRec rec(fPaint, fM, nullptr,
                                        SkShader::ContextRec::kPMColor_DstType,
                                        nullptr);
-        SkShader::Context* ctx = fPaint.getShader()->makeContext(rec, &alloc);
+        SkASSERT(fPaint.getShader()->contextSize(rec) <= sizeof(storage));
+        SkShader::Context* ctx = fPaint.getShader()->createContext(rec, storage);
 
         int count = 100;