[css-values-4] Remove redundant text

Author: frivoal

css-values-4/Overview.bs

@@ -1039,8 +1039,6 @@ Font-relative lengths: the ''em'', ''ex'', ''cap'', ''ch'', ''ic'', ''rem'', ''l
 		<dd>
 			Equal to the computed value of 'line-height' property on the root element,
 			converted to an absolute length by measuring the height line box containing only the strut (See [[CSS2/visudet#strut]]) would have.
-			When specified on the 'font-size' or 'line-height' properties of the root element,
-			the ''rlh'' units refer to the properties' <em>initial value</em>.
 
 			Note: setting the 'height' of an element using either the ''lh'' or the ''rlh'' units
 			does not enable authors to control the actual number of lines in that element.