Bug 89020 [Undo] Operation throws assertion failure if undo limit is set to 0
I20050324-0800 Unfortunately existing clients of text's undo manager were allowed to set any number without failing. This is no longer possible: an assertion failure occurrs if the limit is smaller than 1. I will add code on my side that will handle the negative numbers but the operation history must allow 0.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/operations/DefaultOperationHistory.java
flushRedo(contexts[i]);
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.IOperationHistory#addOperationApprover(org.eclipse.core.commands.operations.IOperationApprover)
	 */
	public void addOperationApprover(IOperationApprover approver) {
		approvers.add(approver);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.IOperationHistory#addOperationHistoryListener(org.eclipse.core.commands.operations.IOperationHistoryListener)
	 */
	public void addOperationHistoryListener(IOperationHistoryListener listener) {
		listeners.add(listener);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.IOperationHistory#canRedo(org.eclipse.core.commands.operations.IUndoContext)
	 */
	public boolean canRedo(IUndoContext context) {
		
		IUndoableOperation operation = getRedoOperation(context);
		return (operation != null && operation.canRedo());
	}
	/*