bean and property atrributes should be optional if value is provided

On a few occasions I've wanted to use `f:display` to render a value which is not a bean property. Here's a contrived example

```

```

But the invocation of `f:display` without a `property` attribute causes an exception. I don't see why I should need to provide either a `property` or `bean` attribute when I'm specifying the field value like this?

Start by locating the f:display tag implementation and the related f:with usage shown in the issue. Reproduce the example with value="${cb.calc()}" and no property or bean attribute; done means the value renders without the current exception while existing property- and bean-based uses continue to work.

Written by the indexing model from the issue text.