Convert NonAALatticeOp to non-legacy GrMeshDrawOp.

Also adds a test factory and fixes a bug in the lattice iter validator where it compared each div value against the start rather than the previous div.

Bug: skia:
Change-Id: I30e9ddfcbaab7829a2f646ad851f99d1e518ab4a
Reviewed-on: https://skia-review.googlesource.com/21871
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/core/SkLatticeIter.cpp b/src/core/SkLatticeIter.cpp
index 4fe9352..9b2a279 100644
--- a/src/core/SkLatticeIter.cpp
+++ b/src/core/SkLatticeIter.cpp
@@ -17,6 +17,7 @@
         if (prev >= divs[i] || divs[i] >= end) {
             return false;
         }
+        prev = divs[i];
     }
 
     return true;