The fix for Bug 531667 (d7ce5978d32a9dd4bf77dfa77e4b1c696992af4a) is
incomplete and doesn't properly update the clipping of a `Path` when a
`Transform` is set. This is because the clipping is calculated by
intersecting the clipping rectangle when the GC instance was created
with the `Path`. The region described by the `Path` is affected by the
transformation, while the region of the rectangle is not.

To fix this problem, the transformation needs to be cleared and
re-applied when resetting the clipping, so that the region of the
clipping rectangle is properly updated.

Closes https://github.com/eclipse-platform/eclipse.platform.swt/issues/3120