Implicitly create `graph_objs` in make_subplots.
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*.

plotly/plotly.py,plotly/python-api,plotly/python-api,plotly/plotly.py,plotly/plotly.py,plotly/python-api