transAxes isn't working properly with scale='log'

[pelson]

Easy to reproduce:

import matplotlib.pyplot as plt
import matplotlib.transforms as mtrans

ax = plt.subplot(122, xscale='log')
t = mtrans.BlendedGenericTransform(ax.transData, ax.transAxes)
plt.plot(50, 0.5, 'ob', transform=t)
plt.show()

Manually resize the window, the point should stay in the middle of the axes, but stays static, as if the values given were in device coordinates.

Likely to be down to a caching issue. Related to #1247. Almost certainly caused by me.

[pelson]

Note: Fixed if the recache method were called by the line's draw method every time (this is equivalent to what used to happen, before I fixed it in #723).

[pelson]

Fixed in #1246.