Fix Perlin noise fuzz issue

src/effects/SkPerlinNoiseShader.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPerlinNoiseShader.h"
 #include "SkColorFilter.h"
 #include "SkReadBuffer.h"
@@ skipping 257 matching lines @@
 
 SkPerlinNoiseShader::SkPerlinNoiseShader(SkPerlinNoiseShader::Type type,
                                          SkScalar baseFrequencyX,
                                          SkScalar baseFrequencyY,
                                          int numOctaves,
                                          SkScalar seed,
                                          const SkISize* tileSize)
   : fType(type)
   , fBaseFrequencyX(baseFrequencyX)
   , fBaseFrequencyY(baseFrequencyY)
-  , fNumOctaves(numOctaves > 255 ? 255 : numOctaves/*[0,255] octaves allowed*/)
+  , fNumOctaves(SkTPin<int>(numOctaves, 0, 255)) // [0,255] octaves allowed
   , fSeed(seed)
   , fTileSize(nullptr == tileSize ? SkISize::Make(0, 0) : *tileSize)
   , fStitchTiles(!fTileSize.isEmpty())
 {
-    SkASSERT(numOctaves >= 0 && numOctaves < 256);
+    SkASSERT(fNumOctaves >= 0 && fNumOctaves < 256);
 }
 
 SkPerlinNoiseShader::~SkPerlinNoiseShader() {
 }
 
 sk_sp<SkFlattenable> SkPerlinNoiseShader::CreateProc(SkReadBuffer& buffer) {
     Type type = (Type)buffer.readInt();
     SkScalar freqX = buffer.readScalar();
     SkScalar freqY = buffer.readScalar();
     int octaves = buffer.readInt();
@@ skipping 683 matching lines @@
     str->append(" seed: ");
     str->appendScalar(fSeed);
     str->append(" stitch tiles: ");
     str->append(fStitchTiles ? "true " : "false ");
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif