test counting, put dummies in for grid3D calcs

SimPEG/Mesh/NewTreeMesh.py

@@ -375,6 +375,10 @@ class TreeMesh(BaseMesh):
         return np.c_[Ex, Ey][P, :]
 
 
+    @property
+    def gridEz(self):
+        pass
+
     @property
     def gridFx(self):
         if self.dim == 2:
@@ -385,6 +389,10 @@ class TreeMesh(BaseMesh):
         if self.dim == 2:
             return self.gridEx
 
+    @property
+    def gridFz(self):
+        pass
+
     def _push(self, attr, rows):
         self.isNumbered = False
         rows = np.atleast_2d(rows)