Implicitly create graph_objs in make_subplots.

The `__init__` method ends up doing some additional validation, it’s
more performant (and exactly the same), to set an item in layout as a
dict instead of as a *graph_obj*.

Author: theengineear

plotly/tools.py

@@ -1000,8 +1000,7 @@ def _get_anchors(r, c, x_cnt, y_cnt, shared_xaxes, shared_yaxes):
     # Function pasting x/y domains in layout object (2d case)
     def _add_domain(layout, x_or_y, label, domain, anchor, position):
         name = label[0] + 'axis' + label[1:]
-        graph_obj = '{X_or_Y}Axis'.format(X_or_Y=x_or_y.upper())
-        axis = getattr(graph_objs, graph_obj)(domain=domain)
+        axis = {'domain': domain}
         if anchor:
             axis['anchor'] = anchor
         if isinstance(position, float):