Batched implementation of drawLattice() for GPU

src/core/SkLatticeIter.cpp

Index: src/core/SkLatticeIter.cpp
diff --git a/src/core/SkLatticeIter.cpp b/src/core/SkLatticeIter.cpp
index 24ab3f1cbc29a11af6ded16de3965c93ac76b292..0a007e98458c2a1cae34eea9dcc7ec17029582de 100644
--- a/src/core/SkLatticeIter.cpp
+++ b/src/core/SkLatticeIter.cpp
@@ -228,3 +228,9 @@ bool SkLatticeIter::next(SkRect* src, SkRect* dst) {
     }
     return true;
 }
+
+int SkLatticeIter::numRects() const {
+    SkASSERT(fSrcX.count() == fDstX.count() && fSrcY.count() == fDstY.count());
+    SkASSERT(fSrcX.count() >= 2 && fDstX.count() >= 2);
+    return (fSrcX.count() - 1) * (fDstX.count() - 1);
+}