[css-inline-3] remove duplicate word

Author: dauwhe

css-inline-3/Overview.bs

@@ -1251,7 +1251,7 @@ Half-Leading Control: the 'leading-trim' property</h3>
 	<strong>Do not implement (yet).</strong>
 
 	On [=inline boxes=],
-	specifies whether to trim trim the [=content box=]
+	specifies whether to trim the [=content box=]
 	to match its corresponding 'text-edge' metric.
 
 	ISSUE: Should inline boxes automatically do this?