Prevents exceptions from being thrown from the viewer refresh

AdapterFactoryEditingDomain#isStale(Object) throws one exception per
item expanded in the EMF Compare structure merge viewers. For large
models, this can go up to tens of thousands of exception for each
refresh, significantly slowing down the merge operations.

These exceptions are thrown but directly caught and swallowed, so we
can circumvent them altogether.

Change-Id: I924364cbd8b9a8727ba8a80e7a40218c4edc2923
1 file changed