Bug report

Something now breaks this code that used to work. Now, I have to call plt.subplots first and use stackplot on an axis object.

TypeError: stackplot() got multiple values for argument 'x'

from matplotlib import pyplot as plt
plt.stackplot([1,2,3], [1,2,3]) 

Should be equivalent to

fig, ax = plt.subplots()
ax.stackplot([1,2,3], [1,2,3]) 

Matplotlib version

• Operating system:
• Matplotlib version: 3.0.0
• Matplotlib backend (print(matplotlib.get_backend())): 'module://ipykernel.pylab.backend_inline'
• Python version: 3.6.6
• Jupyter version (if applicable): 4.4.0
• Other libraries:

Installed matplotlib using conda with default channel.