[mobile] Refine the downloadable fonts feature (w3c#196)

This includes:

* Adding font-display;
* Adding edgestatus for css-font-loading.

data/css-font-display.json

@@ -0,0 +1,9 @@
+{
+  "TR": "https://www.w3.org/TR/css-fonts-4/#font-display-desc",
+  "feature": "font-display",
+  "impl": {
+    "caniuse": "css-font-rendering-controls",
+    "chromestatus": 4799947908055040,
+    "webkitstatus": "specification-css-font-display"
+  }
+}

data/css-font-loading.json

@@ -1,7 +1,8 @@
 {
   "impl": {
     "caniuse": "font-loading",
-    "chromestatus": 6244676289953792
+    "chromestatus": 6244676289953792,
+    "edgestatus": "CSS Font Loading API"
   },
   "TR": "https://www.w3.org/TR/css-font-loading-3/"
 }

mobile/graphics.html

@@ -42,7 +42,7 @@ <h2>Technologies in progress</h2>
         </div>
 
         <div data-feature="Downloadable fonts">
-          <p>Given the time required for downloading fonts over mobile networks, authors need to adapt their content to the progressive availability of fonts; <a data-featureid="css-font-loading">CSS Font Loading</a> gives the necessary events to developers to enable that adaptation.</p>
+          <p>Given the time required for downloading fonts over mobile networks, authors need to adapt their content to the progressive availability of fonts. <a data-featureid="css-font-loading">CSS Font Loading</a> gives the necessary events and interfaces to developers to enable that adaptation. The <a data-featureid="css-font-display"><code>font-display</code></a> descriptor for <code>@font-face</code> and <code>@font-feature-values</code> rules can also be used to control how a downloadable font renders before it is fully loaded.</p>
           <p>Font variations along different axes (width, weight, optical size) can be encoded in a single font file. The <a data-featureid="css-fonts-variable">Font variation properties</a> in CSS allow finer control over usage of font variants and can further help developers avoid unnecessary network requests to fetch additional variants of a font.</p>
         </div>