Soft masks can be enabled/disabled at anytime and at different
points in the save/restore stack. This can lead to
the amount of save/restores becoming unbalanced across the
two canvases. Instead of save/restoring on the temporary canvas
change it so we only track state on the main (suspended canvas).
I was also getting an out balance stack from patterns, so I've also
fixed that and added a warning that will at least show up on chrome.
It would be nice to add this so Firefox at some point too.
Fixes#11328, #14297 and bug 1755507
