Increase bits for effect attribute key

src/gpu/gl/GrGLEffect.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGLSL.h"
 #include "GrGLEffect.h"
 
@@ skipping 21 matching lines @@
     return key;
 }
 
 GrGLEffect::EffectKey GrGLEffect::GenAttribKey(const GrEffectStage& stage) {
     EffectKey key = 0;
 
     int numAttributes = stage.getVertexAttribIndexCount();
     GrAssert(numAttributes <= 2);
     const int* attributeIndices = stage.getVertexAttribIndices();
     for (int index = 0; index < numAttributes; ++index) {
-        EffectKey value = attributeIndices[index] << 2*index;
+        EffectKey value = attributeIndices[index] << 3*index;
         GrAssert(0 == (value & key)); // keys for each attribute ought not to overlap
         key |= value;
     }
 
     return key;
 }