Don't show the currently-completing thing at the cursor in JS files

Fixes #6693

(cherry picked from commit 124bd517e7)

tests/cases/fourslash/getJavaScriptCompletions20.ts

@@ -0,0 +1,21 @@
+/// <reference path="fourslash.ts" />
+
+// @allowNonTsExtensions: true
+// @Filename: file.js
+//// /**
+////  * A person
+////  * @constructor
+////  * @param {string} name - The name of the person.
+////  * @param {number} age - The age of the person.
+////  */
+//// function Person(name, age) {
+////     this.name = name;
+////     this.age = age;
+//// }
+//// 
+//// 
+//// Person.getName = 10;
+//// Person.getNa/**/ = 10;
+
+goTo.marker();
+verify.not.memberListContains('getNa');