[css-overflow] Test coverage

Author: frivoal

css-overflow-4/Overview.bs

@@ -1055,6 +1055,7 @@ Indicating Block-Axis Overflow: the 'block-ellipsis' property</h3>
 
 		<wpt>
 			block-ellipsis-041.html
+			line-clamp-with-floats-012.html
 		</wpt>
 
 	Text <a href="https://www.w3.org/TR/css-text-3/#justification">alignment and justification</a>
@@ -1886,6 +1887,7 @@ Handling of Excess Content: the 'continue' property</h3>
 		line-clamp-with-floats-006.html
 		line-clamp-with-floats-010.html
 		line-clamp-with-floats-011.html
+		line-clamp-with-floats-012.html
 	</wpt>
 
 	If a [=block container=] contains a [=clamp point=],