Forgetting classes in an Environment

http://build.squeak.org/job/SqueakTrunk/338/testReport/KernelTests.Methods/CompiledMethodTest/testMethodClass/

shows a test failure because the test asserts that a CompiledMethod
can still reference its class after a class has been removed.

However, Environments-cwp.25 explicitly nils out the value of the
ClassBinding in the Environment's undeclared.

If this is correct behaviour, then CompiledMethod needs adjusting.
#methodClass assumes that it can look up this binding, whether
Undeclared or not, by inspecting its literals.

frank