[css-pseudo-4] ::first-line cannot cross non-block element formatting context boundary. Also except table captions. w3c#1174 fixes w3c#1174

Author: fantasai

css-pseudo-4/Overview.bs

@@ -155,7 +155,8 @@ Finding the First Formatted Line</h4>
     (assuming that both <code>P</code> and <code>DIV</code> are blocks).
   </div>
 
-  The first line of a table-cell or inline-block
+  The first line of a [=block container=] which does not participate in a [=block formatting context=]
+  (and likewise the first line of a [=table caption=])
   cannot be the first formatted line of an ancestor element.
   Thus, in <code>&lt;DIV&gt;&lt;P STYLE="display: inline-block"&gt;Hello&lt;BR&gt;Goodbye&lt;/P&gt; etcetera&lt;/DIV&gt;</code>
   the first formatted line of the <code>DIV</code> is not the line "Hello".