use const instead of let for new class iife assignments (#36907)

Author: weswigham

src/compiler/transformers/ts.ts

@@ -673,7 +673,7 @@ namespace ts {
                             /*type*/ undefined,
                             iife
                         )
-                    ], languageVersion > ScriptTarget.ES5 ? NodeFlags.Let : undefined)
+                    ], languageVersion > ScriptTarget.ES5 ? NodeFlags.Const : undefined)
                 );
 
                 setOriginalNode(varStatement, node);

tests/baselines/reference/awaitAndYieldInProperty.js

@@ -20,7 +20,7 @@ async function* test(x: Promise<string>) {
 //// [awaitAndYieldInProperty.js]
 async function* test(x) {
     var _a, _b, _c, _d, _e;
-    let C = /** @class */ (() => {
+    const C = /** @class */ (() => {
         var _e, _f, _g, _h;
         class C {
             constructor() {

tests/baselines/reference/classDeclarationCheckUsedBeforeDefinitionInItself.js

@@ -4,7 +4,7 @@ class C3 {
 }
 
 //// [classDeclarationCheckUsedBeforeDefinitionInItself.js]
-let C3 = /** @class */ (() => {
+const C3 = /** @class */ (() => {
     class C3 {
     }
     C3.intance = new C3(); // ok

tests/baselines/reference/computedPropertyNames12_ES6.js

@@ -20,7 +20,7 @@ class C {
 var s;
 var n;
 var a;
-let C = /** @class */ (() => {
+const C = /** @class */ (() => {
     var _a, _b, _c;
     class C {
         constructor() {

tests/baselines/reference/computedPropertyNamesWithStaticProperty.js

@@ -11,7 +11,7 @@ class C {
 }
 
 //// [computedPropertyNamesWithStaticProperty.js]
-let C = /** @class */ (() => {
+const C = /** @class */ (() => {
     class C {
         get [C.staticProp]() {
             return "hello";

tests/baselines/reference/decoratedClassExportsCommonJS1.js

@@ -15,7 +15,7 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
     return c > 3 && r && Object.defineProperty(target, key, r), r;
 };
 Object.defineProperty(exports, "__esModule", { value: true });
-let Testing123 = /** @class */ (() => {
+const Testing123 = /** @class */ (() => {
     var Testing123_1;
     let Testing123 = Testing123_1 = class Testing123 {
     };

tests/baselines/reference/decoratedClassExportsCommonJS2.js

@@ -13,7 +13,7 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
     return c > 3 && r && Object.defineProperty(target, key, r), r;
 };
 Object.defineProperty(exports, "__esModule", { value: true });
-let Testing123 = /** @class */ (() => {
+const Testing123 = /** @class */ (() => {
     var Testing123_1;
     let Testing123 = Testing123_1 = class Testing123 {
     };

tests/baselines/reference/decoratedClassFromExternalModule.js

@@ -17,7 +17,7 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
     return c > 3 && r && Object.defineProperty(target, key, r), r;
 };
 function decorate(target) { }
-let Decorated = /** @class */ (() => {
+const Decorated = /** @class */ (() => {
     let Decorated = class Decorated {
     };
     Decorated = __decorate([

tests/baselines/reference/decoratedDefaultExportsGetExportedAmd.js

@@ -24,7 +24,7 @@ define(["require", "exports"], function (require, exports) {
     "use strict";
     Object.defineProperty(exports, "__esModule", { value: true });
     var decorator;
-    let Foo = /** @class */ (() => {
+    const Foo = /** @class */ (() => {
         let Foo = class Foo {
         };
         Foo = __decorate([
@@ -45,7 +45,7 @@ define(["require", "exports"], function (require, exports) {
     "use strict";
     Object.defineProperty(exports, "__esModule", { value: true });
     var decorator;
-    let default_1 = /** @class */ (() => {
+    const default_1 = /** @class */ (() => {
         let default_1 = class {
         };
         default_1 = __decorate([

tests/baselines/reference/decoratedDefaultExportsGetExportedCommonjs.js

@@ -23,7 +23,7 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
 };
 Object.defineProperty(exports, "__esModule", { value: true });
 var decorator;
-let Foo = /** @class */ (() => {
+const Foo = /** @class */ (() => {
     let Foo = class Foo {
     };
     Foo = __decorate([
@@ -42,7 +42,7 @@ var __decorate = (this && this.__decorate) || function (decorators, target, key,
 };
 Object.defineProperty(exports, "__esModule", { value: true });
 var decorator;
-let default_1 = /** @class */ (() => {
+const default_1 = /** @class */ (() => {
     let default_1 = class {
     };
     default_1 = __decorate([