Let's take another shot at answering this...
When using the white-space
pre directive, white spaces are displayed literally by the browser. Line breaks, spaces, and tabs are shown as they are written (br tags also act as line breaks). For example:
<div> hello
world</div>
...will be displayed as:
hello
world
The float:right directive removes the element from the normal text flow and positions it to the right of its container, allowing text and other elements to wrap around it.
In Firefox, the floated div will fill the available space horizontally, causing it to go to the next line. However, in Chrome, the floated element stays on the same line (although both divs are displayed as block elements taking up the full width). This difference can be seen in this fiddle.
http://jsfiddle.net/k5aueocr/
Since the white-space:pre directive instructs the browser to interpret each character precisely as written, combining it with a span that floats to the right may result in unexpected behavior. Both browsers are following their specifications correctly, but mixing these CSS properties may not produce the desired outcome.