[css-display] Export some terms.

css-display/Overview.bs

@@ -41,15 +41,15 @@ Introduction</h2>
 
 	<p><em>This section is normative.</em>
 
-	CSS takes a source document, organized as a <dfn lt="element tree">tree</dfn> of <dfn>elements</dfn> and <dfn>text nodes</dfn>,
+	CSS takes a source document, organized as a <dfn export for=CSS lt="element tree">tree</dfn> of <dfn export for=CSS lt="element">elements</dfn> and <dfn export for=CSS lt="text node">text nodes</dfn>,
 	and renders it onto a <a href="https://www.w3.org/TR/CSS2/intro.html#canvas">canvas</a> (such as your screen, a piece of paper, or an audio stream).
 	To do this, it generates an intermediary structure,
-	the <dfn export>box tree</dfn>,
+	the <dfn export for=CSS>box tree</dfn>,
 	which represents the formatting structure of the rendered document.
-	Each <dfn export>box</dfn> in the <a>box tree</a>
+	Each <dfn export for=CSS>box</dfn> in the <a>box tree</a>
 	represents its corresponding <a>element</a> (or <a>pseudo-element</a>)
 	in space and/or time on the canvas,
-	while each <dfn export>text run</dfn> in the <a>box tree</a>
+	while each <dfn export for=CSS>text run</dfn> in the <a>box tree</a>
 	likewise represents the contents of its corresponding <a>text nodes</a>.
 
 	To create the <a>box tree</a>,
@@ -76,7 +76,7 @@ Introduction</h2>
 	Similarly, each contiguous sequence of sibling <a>text nodes</a> generates a <a>text run</a>,
 	which is assigned the same styles as the generating <a>text nodes</a>.
 
-	An <dfn lt="anonymous|anonymous box" export>anonymous box</dfn> is is a box that is not associated with any element.
+	An <dfn for=CSS lt="anonymous|anonymous box" export>anonymous box</dfn> is is a box that is not associated with any element.
 	<a>Anonymous boxes</a> are generated in certain circumstances
 	to fix up the <a>box tree</a> when it requires a particular nested structure
 	that is not provided by the boxes generated from the <a>element tree</a>.