Improve error reporting in ProcessorCloneTest.

Previously, when REPORTER_ASSERT reported a failure, there was no
additional information describing the FP that could not be cloned in the
error log. Now, we print out a very simple tree of the FP and its
children.

Change-Id: I141cfb17ca431864a6f555d56f0335293f259c4e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/296452
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
1 file changed