Remove unused fRequiresVertexShader data member from OptDrawState

src/gpu/GrOptDrawState.h

Index: src/gpu/GrOptDrawState.h
diff --git a/src/gpu/GrOptDrawState.h b/src/gpu/GrOptDrawState.h
index 9445d334a2785ac82445324735456de25794c010..b4f59d3a7b09f0dd1ff51f20ed6721318518f191 100644
--- a/src/gpu/GrOptDrawState.h
+++ b/src/gpu/GrOptDrawState.h
@@ -25,7 +25,6 @@ public:
 
     bool readsDst() const { return fReadsDst; }
     bool readsFragPosition() const { return fReadsFragPosition; }
-    bool requiresVertexShader() const { return fRequiresVertexShader; }
     bool requiresLocalCoordAttrib() const { return fRequiresLocalCoordAttrib; }
 
     ///////////////////////////////////////////////////////////////////////////
@@ -123,7 +122,6 @@ private:
     // These flags give aggregated info on the effect stages that are used when building programs.
     bool            fReadsDst;
     bool            fReadsFragPosition;
-    bool            fRequiresVertexShader;
     bool            fRequiresLocalCoordAttrib;
 
     SkAutoSTArray<4, GrVertexAttrib> fOptVA;