Flex preview for text containers

There is a bug in the preview of elements that contain text, like h and p tags: When the display of said elements is set to flex, the text characters are treated like separate elements and are spatially distributed according to the flex display properties. Of course the rendered result in the browser is correct, but the preview in BSS is messed up.

To see an example: Place a h1 tag in the page. Add the following CSS:

h1 { display:flex; flex-direction:column; }