fixed "mNan" id in scroll markers (#1414)

Author: LordBaryhobal

coverage/htmlfiles/coverage_html.js

@@ -553,7 +553,7 @@ coverage.build_scroll_markers = function () {
         'p.show_run, p.show_mis, p.show_exc, p.show_exc, p.show_par'
     ).forEach(element => {
         const line_top = Math.floor(element.offsetTop * marker_scale);
-        const line_number = parseInt(element.id.substr(1));
+        const line_number = parseInt(element.querySelector(".n a").id.substr(1));
 
         if (line_number === previous_line + 1) {
             // If this solid missed block just make previous mark higher.