Fixed error when normal.z = 1 in GPUs with binary16 floats

src/core/SkNormalSource.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkError.h"
 #include "SkErrorInternals.h"
 #include "SkLightingShader.h"
@@ skipping 91 matching lines @@
 
             SkString dstNormalColorName("dstNormalColor");
             this->emitChild(0, nullptr, &dstNormalColorName, args);
             fragBuilder->codeAppendf("vec3 normal = normalize(%s.rgb - vec3(0.5));",
                                      dstNormalColorName.c_str());
 
             // TODO: inverse map the light direction vectors in the vertex shader rather than
             // transforming all the normals here!
 
             // If there's no x & y components, return (0, 0, +/- 1) instead to avoid division by 0
-            fragBuilder->codeAppend( "if (abs(normal.z) > 0.9999) {");
+            fragBuilder->codeAppend( "if (abs(normal.z) > 0.999) {");
             fragBuilder->codeAppendf("    %s = normalize(vec4(0.0, 0.0, normal.z, 0.0));",
                     args.fOutputColor);
             // Else, Normalizing the transformed X and Y, while keeping constant both Z and the
             // vector's angle in the XY plane. This maintains the "slope" for the surface while
             // appropriately rotating the normal for any anisotropic scaling that occurs.
             // Here, we call scaling factor the number that must divide the transformed X and Y so
             // that the normal's length remains equal to 1.
             fragBuilder->codeAppend( "} else {");
             fragBuilder->codeAppendf("    vec2 transformed = %s * normal.xy;",
                     xformUniName);
@@ skipping 191 matching lines @@
     return sk_make_sp<NormalMapSourceImpl>(std::move(map), invCTM);
 }
 
 ////////////////////////////////////////////////////////////////////////////
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkNormalSource)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(NormalMapSourceImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END
 
 ////////////////////////////////////////////////////////////////////////////