[css-overflow-4] Clamp containers clip floats, instead of growing

See #12665

Author: frivoal

css-overflow-4/Overview.bs

@@ -1706,12 +1706,13 @@ Handling of Excess Content: the 'continue' property</h3>
 		line-clamp-auto-005.html
 	</wpt>
 
-	NOTE: If there are any floats before the [=clamp point=],
-	the [=line-clamp container=]'s automatic size must grow to encompass the clearance,
-	just like it would if it were a regular [=block formatting context=] root
-	that only contained its contents before the [=clamp point=].
-	This is regardless of whether this would cause any content after the [=clamp point=]
-	to be within the container's bounds.
+	Within a [=line-clamp container=],
+	floats which have not been made into [=invisible boxes=]
+	must be visually clipped to the [=content edge=]
+	of the [=line-clamp container=].
+	They do not introduce any clearance
+	that would make the [=line-clamp container=] increase its height,
+	and do not contribute to the [=scrollable overflow area=].
 
 <h4 id=discarding-content>Discarding Content</h4>