Add option to add precision to varyings in shader

src/gpu/effects/GrBezierEffect.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 "gl/builders/GrGLProgramBuilder.h"
 #include "GrBezierEffect.h"
 
@@ skipping 324 matching lines @@
 void GrGLCubicEffect::emitCode(GrGLFullProgramBuilder* builder,
                                const GrDrawEffect& drawEffect,
                                const GrEffectKey& key,
                                const char* outputColor,
                                const char* inputColor,
                                const TransformedCoordsArray&,
                                const TextureSamplerArray& samplers) {
     const char *vsName, *fsName;
 
     builder->addVarying(kVec4f_GrSLType, "CubicCoeffs",
-                              &vsName, &fsName);
+                              &vsName, &fsName, GrGLShaderVar::kHigh_Precision);
 
     GrGLVertexShaderBuilder* vsBuilder = builder->getVertexShaderBuilder();
     const SkString* attr0Name =
         vsBuilder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0]);
     vsBuilder->codeAppendf("%s = %s;", vsName, attr0Name->c_str());
 
     GrGLFragmentShaderBuilder* fsBuilder = builder->getFragmentShaderBuilder();
 
     GrGLShaderVar edgeAlpha("edgeAlpha", kFloat_GrSLType, 0, GrGLShaderVar::kHigh_Precision);
     GrGLShaderVar dklmdx("dklmdx", kVec3f_GrSLType, 0, GrGLShaderVar::kHigh_Precision);
@@ skipping 115 matching lines @@
                                     GrTexture*[]) {
     GrEffect* effect;
     do {
         GrEffectEdgeType edgeType = static_cast<GrEffectEdgeType>(
                                                     random->nextULessThan(kGrEffectEdgeTypeCnt));
         effect = GrCubicEffect::Create(edgeType, caps);
     } while (NULL == effect);
     return effect;
 }