Revert of Sketch SkPMFloat

bench/PMFloatBench.cpp

-#include "Benchmark.h"
-#include "SkPMFloat.h"
-#include "SkRandom.h"
-
-struct PMFloatBench : public Benchmark {
-    explicit PMFloatBench(bool clamp) : fClamp(clamp) {}
-
-    const char* onGetName() SK_OVERRIDE { return fClamp ? "SkPMFloat_clamp" : "SkPMFloat_get"; }
-    bool isSuitableFor(Backend backend) SK_OVERRIDE { return backend == kNonRendering_Backend; }
-
-    void onDraw(const int loops, SkCanvas* canvas) SK_OVERRIDE {
-        SkRandom rand;
-        for (int i = 0; i < loops; i++) {
-            SkPMColor c = SkPreMultiplyColor(rand.nextU());
-            SkPMFloat pmf;
-            pmf.set(c);
-            SkPMColor back = fClamp ? pmf.clamped() : pmf.get();
-            if (c != back) { SkFAIL("no joy"); }  // This conditional makes this not compile away.
-        }
-    }
-
-    bool fClamp;
-};
-DEF_BENCH(return new PMFloatBench( true);)
-DEF_BENCH(return new PMFloatBench(false);)