Extra spaces are inserted when macro placeholders are inserted

Steps to reproduce

1. add / edit a page and insert a macro placeholder

expected: single line inserted before and after macro placeholder
actual: two lines are inserted before and after macro placeholder

If the placeholder is inside a parent macro placeholder, then spaces will be added to the parent placeholder as well.

However, if the user does not delete these extra spaces inside the parent placeholder, no extra spaces will be added inside the macro placeholder. That is, there always seems to be two extra spaces in the parent macroplaceholder.

Reproduced on:

Environment

Trunk
Stable

Browsers

IE8
IE9
FF7
Chrome