[RB] Add a test for ProtectInstanceVariable with a accessor user in a subclass.

[Ducasse]

Right now the only test we have is the following one.

testProtectInstanceVariable
	| refactoring class |
	refactoring := self createRefactoringWithArguments:
		{('rewrite' , 'Rule1') . #RBSubclassOfClassToRename}.
	self executeRefactoring: refactoring.
	class := refactoring model classNamed: #RBSubclassOfClassToRename.
	self assert: (class parseTreeForSelector: #calls1) equals: (self parseMethod: 'calls1
								^rewriteRule1 := (rewriteRule1 := self calls)').
	self assert: (class parseTreeForSelector: #calls) equals: (self parseMethod: 'calls
								^rewriteRule1 := rewriteRule1 , rewriteRule1').
	self deny: (class directlyDefinesMethod: ('rewrite' , 'Rule1') asSymbol).
	self deny: (class directlyDefinesMethod: ('rewrite' , 'Rule1:') asSymbol)