Rewrite logic as per latest syntax -@locks review

Author: rajakvk

app/components/ember-anchor.js

@@ -1,3 +1,4 @@
+/* eslint-disable ember/classic-decorator-no-classic-methods */
 import AnchorComponent from 'ember-anchor/components/ember-anchor';
 import config from 'ember-api-docs/config/environment';
 import getOffset from 'ember-api-docs/utils/get-offset';
@@ -6,7 +7,7 @@ export default class EmberAnchor extends AnchorComponent {
   // This overrides Ember Anchor to support scrolling within a fixed position element
   _scrollToElemPosition() {
     let qp = this.anchorQueryParam;
-    let qpVal = this[this['attrs.a'] ? 'a' : `controller.${qp}`];
+    let qpVal = this.a ?? this.controller[qp];
     let elem = document.querySelector(`[data-${qp}="${qpVal}"]`);
 
     if (elem && elem.offsetHeight) {