Refactor GrGLUniformManager::UniformHandle to initialize itself by default

src/gpu/gl/GrGpuGL_program.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGpuGL.h"
 
 #include "GrEffect.h"
 #include "GrGLEffect.h"
 #include "SkTSearch.h"
 
 typedef GrGLUniformManager::UniformHandle UniformHandle;
-static const UniformHandle kInvalidUniformHandle = GrGLUniformManager::kInvalidUniformHandle;
 
 struct GrGpuGL::ProgramCache::Entry {
     SK_DECLARE_INST_COUNT_ROOT(Entry);
     Entry() : fProgram(NULL), fLRUStamp(0) {}
 
     SkAutoTUnref<GrGLProgram>   fProgram;
     unsigned int                fLRUStamp;
 };
 
 SK_DEFINE_INST_COUNT(GrGpuGL::ProgramCache::Entry);
@@ skipping 373 matching lines @@
                          GrGLAttribTypeToLayout(attribType).fCount,
                          GrGLAttribTypeToLayout(attribType).fType,
                          GrGLAttribTypeToLayout(attribType).fNormalized,
                          stride,
                          reinterpret_cast<GrGLvoid*>(
                          vertexOffsetInBytes + vertexAttrib->fOffset));
     }
 
     attribState->disableUnusedAttribArrays(this, usedAttribArraysMask);
 }