SVGs containing clipped elements can clip the entire paint editor canvas

[adroitwhiz]

Expected Behavior

Elements with a clip mask should not affect paint editor operations

Actual Behavior

If an ungrouped element has a clip mask, or if you ungroup an element with a clip mask, the mask will apply to the entire paint editor canvas:

Steps to Reproduce

1. Import an SVG containing a clip mask
2. Ungroup the clipped elements
3. Attempt to use the paint editor, and note that all new shapes are masked.

Operating System and Browser

All

[fsih]

We decided not to support some of the harder to deal with features of SVG in the paint editor, like the < mask >, < use >, and < filter > tags. We didn't really decide what exactly to do with them... so right now they just do weird stuff. It's true that masks are pretty common "in the wild" and people have trouble importing them a lot, and it would be nice if we dealt with them better.