Set analytic AA as default.

src/core/SkXfermode.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkXfermode.h"
 #include "SkXfermode_proccoeff.h"
 #include "SkColorPriv.h"
@@ skipping 931 matching lines @@
     for (int i = 0; i < 4; ++i) {
         SkASSERT(r.fVec[i] >= min && r.fVec[i] <= max);
     }
 #endif
 }
 
 template <Sk4f (blend)(const Sk4f&, const Sk4f&)> SkPM4f proc_4f(const SkPM4f& s, const SkPM4f& d) {
     assert_unit(s);
     assert_unit(d);
     SkPM4f r = as_pm4f(blend(as_4f(s), as_4f(d)));
-    assert_unit(r);
+    // Turn this assert off for now because srgb conversions may end up in rgb > a
+    // assert_unit(r);

[mtklein_C, 2016/11/02 18:48:19]

I'm hoping to obsolete this code over time so I don't mind just disabling the
assert here.

     return r;
 }
 
 const ProcCoeff gProcCoeffs[] = {
     { clear_modeproc,       proc_4f<clear_4f>,      SkXfermode::kZero_Coeff,    SkXfermode::kZero_Coeff },
     { src_modeproc,         proc_4f<src_4f>,        SkXfermode::kOne_Coeff,     SkXfermode::kZero_Coeff },
     { dst_modeproc,         proc_4f<dst_4f>,        SkXfermode::kZero_Coeff,    SkXfermode::kOne_Coeff  },
     { srcover_modeproc,     proc_4f<srcover_4f>,    SkXfermode::kOne_Coeff,     SkXfermode::kISA_Coeff  },
     { dstover_modeproc,     proc_4f<dstover_4f>,    SkXfermode::kIDA_Coeff,     SkXfermode::kOne_Coeff  },
     { srcin_modeproc,       proc_4f<srcin_4f>,      SkXfermode::kDA_Coeff,      SkXfermode::kZero_Coeff },
@@ skipping 559 matching lines @@
         case SkBlendMode::kHue:
         case SkBlendMode::kSaturation:
         case SkBlendMode::kColor:
         case SkBlendMode::kLuminosity: return false;  // TODO
     }
     if (p) {
         p->append(stage);
     }
     return true;
 }