Avoid updating glPathStencilFunc unless it changes

src/gpu/GrStencil.h

Index: src/gpu/GrStencil.h
diff --git a/src/gpu/GrStencil.h b/src/gpu/GrStencil.h
index d94a45fad2bef6e6cc0a7416c511b68b74fc05f4..67baef9cd94e50da7e0400eef8e53883b83808bd 100644
--- a/src/gpu/GrStencil.h
+++ b/src/gpu/GrStencil.h
@@ -280,7 +280,9 @@ public:
         fPassOps[0] = (GrStencilOp)(uint8_t)-1;
         fFlags = 0;
     }
-
+    bool isValid() const {

[bsalomon, 2016/01/22 14:38:38]

as implemented, shouldn't this be called isInvalid()?

Other than that this lgtm.

[Kimmo Kinnunen, 2016/01/25 08:33:13]

Ah, where is my head at.. I fixed this and changed the style sligthly, is it
still ok?

+        return fPassOps[0] == static_cast<GrStencilOp>(static_cast<uint8_t>(-1)) && fFlags == 0;
+    }
     bool operator == (const GrStencilSettings& s) const {
         static const size_t gCompareSize = sizeof(GrStencilSettings) -
                                            sizeof(fFlags);