Merge pull request #16697 from RyanCavanaugh/preserveMethodComments

Preserve method comments in JS->ES6 conversion.

tests/cases/fourslash/convertFunctionToEs6ClassJsDoc.ts

@@ -0,0 +1,45 @@
+/// <reference path='fourslash.ts' />
+
+// @allowNonTsExtensions: true
+// @Filename: test123.js
+//// function fn() {
+////     /** neat! */
+////     this.x = 100;
+//// }
+////
+//// /** awesome
+////   * stuff
+////   */
+//// fn.prototype.arr = () => { return ""; }
+//// /** great */
+//// fn.prototype.arr2 = () => [];
+//// 
+//// /**
+////   * This is a cool function!
+//// */
+//// /*1*/fn.prototype.bar = function (x, y, z) {
+////     this.x = y;
+//// };
+
+verify.fileAfterApplyingRefactorAtMarker('1',
+`class fn {
+    constructor() {
+        /** neat! */
+        this.x = 100;
+    }
+    /** awesome
+      * stuff
+      */
+    arr() { return ""; }
+    /** great */
+    arr2() { return []; }
+    /**
+      * This is a cool function!
+    */
+    bar(x, y, z) {
+        this.x = y;
+    }
+}
+
+
+`, 'Convert to ES2015 class', 'convert');