Merge pull request #723 from mathjax/fix-char-usage

Fix several issues with CHTML adaptive CSS.

Author: dpvc

ts/output/chtml/FontData.ts

@@ -230,8 +230,9 @@ export class CHTMLFontData extends FontData<CHTMLCharOptions, CHTMLVariantData,
    * @param {CHTMLDelimiterData} data  The data for the delimiter whose CSS is to be added
    */
   protected addDelimiterStyles(styles: StyleList, n: number, data: CHTMLDelimiterData) {
-    const c = this.charSelector(n);
+    let c = this.charSelector(n);
     if (data.c && data.c !== n) {
+      c = this.charSelector(data.c);
       styles['.mjx-stretched mjx-c' + c + '::before'] = {
         content: this.charContent(data.c)
       };

ts/output/chtml/Wrappers/TextNode.ts

@@ -87,7 +87,7 @@ CommonTextNodeMixin<CHTMLConstructor<any, any, any>>(CHTMLWrapper) {
                       this.jax.unknownText(String.fromCodePoint(n), variant) :
                       this.html('mjx-c', {class: this.char(n) + font}));
         adaptor.append(parent, node);
-        this.font.charUsage.add([variant, n]);
+        !data.unknown && this.font.charUsage.add([variant, n]);
       }
     }
   }

ts/output/chtml/Wrappers/mo.ts

@@ -158,6 +158,7 @@ CommonMoMixin<CHTMLConstructor<any, any, any>>(CHTMLWrapper) {
   protected stretchHTML(chtml: N) {
     const c = this.getText().codePointAt(0);
     this.font.delimUsage.add(c);
+    this.childNodes[0].markUsed();
     const delim = this.stretch;
     const stretch = delim.stretch;
     const content: N[] = [];