Fixes #11 lastChange on 'value' in condition.value.
The ValueChangeTransformer was not recursive on transformUnaryExpression in
the case that the operator was not ++ or --.
And object properties set to undefined are silently dropped by JSON, so
the types of properties has to be sent as well, and the undefined has
to be reconstructed when we get back from the extractTracepoint eval().

Added test case lastChangeConditionValue