Fix having tutorials update if a text is deleted.

Tutorials should rerun whenever the contents change.  Some code designed
to perform updates when separate code blocks were edited happened to
prevent deleting text from triggering the update.

tutorials/common/tutorials.js

@@ -192,8 +192,8 @@ function process_block_debounce(selector, debounce) {
     processBlockInfo.lastelem = selector;
     if (!debounce) {
       process_block(selector);
+      return;
     }
-    return;
   }
   processBlockInfo.timer = window.setTimeout(function () {
     process_block(processBlockInfo.lastelem);