Return the promise when requesting MathJax render

Author: bnmnetp

runestone/common/js/runestonebase.js

@@ -449,7 +449,7 @@ export default class RunestoneBase {
             // See - https://docs.mathjax.org/en/latest/advanced/typeset.html
             // Per the above we should keep track of the promises and only call this
             // a second time if all previous promises have resolved.
-            MathJax.typesetPromise([component]);
+            return MathJax.typesetPromise([component]);
         }
     }
 }