Rename private attribute _element to _el

Change-Id: I9c7a31bd6844636737ffa6456562b997f5e370a3
diff --git a/dev/js/src/vc/fragment.js b/dev/js/src/vc/fragment.js
index 0f155ff..72bd80e 100644
--- a/dev/js/src/vc/fragment.js
+++ b/dev/js/src/vc/fragment.js
@@ -89,12 +89,12 @@
      * Get the element associated with the virtual corpus
      */
     element : function () {
-      if (this._element !== undefined) {
-        return this._element;
+      if (this._el !== undefined) {
+        return this._el;
       };
 
       // Initialize element
-      const e = this._element = document.createElement('div');
+      const e = this._el = document.createElement('div');
       e.classList.add('vc', 'fragment');
 
       // Prepend info text