Merge pull request #950 from edx/gprice/dialog-role

Add ARIA dialog role to Markdown editor dialogs

lms/static/js/Markdown.Editor.js

@@ -1063,6 +1063,7 @@
 
             // The main dialog box.
             dialog = doc.createElement("div");
+            dialog.setAttribute("role", "dialog");
             dialog.className = "wmd-prompt-dialog";
             dialog.style.padding = "10px;";
             dialog.style.position = "fixed";