Remove gr from the list of attr() types.

Author: tabatkins

css3-values/Overview.html

@@ -1617,8 +1617,6 @@ <h3 id=attr><span class=secno>8.3. </span> Attribute References: &lsquo;<a
 
    <dt>&lsquo;<code class=css>px</code>&rsquo;
 
-   <dt>&lsquo;<code class=css>gr</code>&rsquo;
-
    <dt>&lsquo;<a href="#rem-unit"><code class=css>rem</code></a>&rsquo;
 
    <dt>&lsquo;<a href="#vw-unit"><code class=css>vw</code></a>&rsquo;

css3-values/Overview.src.html

@@ -1128,7 +1128,6 @@ <h3 id="attr">
 		<dt>''em''
 		<dt>''ex''
 		<dt>''px''
-		<dt>''gr''
 		<dt>''rem''
 		<dt>''vw''
 		<dt>''vh''