These (rather long) methods are nearly identical. SmalltalkImage is a
bit more demanding re GC, and double-GCs before the
large-chunk-of-sameness. Other than that, the only difference I can
see is a logging statement printing to Transcript.

Oh, it's worse: ReleaseBuilder also has the same code, except that
ReleaseBuilder inspects SystemNavigation default while the other two
inspect SystemNavigation default obsoleteBehaviors.

(http://bugs.squeak.org/view.php?id=7754)

frank