Focus on the current file in the source file sidebar

Author: GuillaumeGomez

src/librustdoc/html/static/source-script.js

@@ -140,4 +140,9 @@ function createSourceSidebar() {
     });
 
     main.insertBefore(sidebar, main.firstChild);
+    // Focus on the current file in the source files sidebar.
+    var selected_elems = Array.prototype.slice.call(sidebar.getElementsByClassName("selected"));
+    if (selected_elems.length > 0) {
+        selected_elems[0].focus();
+    }
 }