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
}
			return OPERATION_INVALID_STATUS;
		}
		return doUndo(monitor, info, operation, true);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.commands.operations.IOperationHistory#undoOperation(org.eclipse.core.commands.operations.IUndoableOperation, org.eclipse.core.runtime.IProgressMonitor, org.eclipse.core.runtime.IAdaptable)
	 */
	public IStatus undoOperation(IUndoableOperation operation, IProgressMonitor monitor, IAdaptable info) throws ExecutionException{
		Assert.isNotNull(operation);
		IStatus status;
		if (operation.canUndo()) {
			status = getUndoApproval(operation, info);
			if (status.isOK()) {
				status = doUndo(monitor, info, operation, false);
			}
		} else {
			if (DEBUG_OPERATION_HISTORY_UNEXPECTED) {
				System.out.print("OPERATIONHISTORY >>> Undo operation not valid - ");  
				System.out.print(operation);
				System.out.println();
			}
			status = OPERATION_INVALID_STATUS;
		}
		return status;
	}
	/*
	 * (non-Javadoc)