Name conflict between JS keywords and generated function names when transpiling classes to ES5

[robinWongM]

TypeScript 3.6.3
Playground link

Compiler Options:

{
  "compilerOptions": {
    "noImplicitAny": true,
    "strictNullChecks": true,
    "strictFunctionTypes": true,
    "strictPropertyInitialization": true,
    "strictBindCallApply": true,
    "noImplicitThis": true,
    "noImplicitReturns": true,
    "alwaysStrict": true,
    "allowUnreachableCode": false,
    "allowUnusedLabels": false,
    "downlevelIteration": false,
    "noEmitHelpers": false,
    "noLib": false,
    "noStrictGenericChecks": false,
    "noUnusedLocals": false,
    "noUnusedParameters": false,
    "esModuleInterop": true,
    "preserveConstEnums": false,
    "removeComments": false,
    "skipLibCheck": false,
    "checkJs": false,
    "allowJs": false,
    "experimentalDecorators": false,
    "emitDecoratorMetadata": false,
    "target": "ES5",
    "module": "ESNext"
  }
}

Input:

let exports: any;
exports.default = class {
    constructor() {
        // do nothing
    }
}

Output:

"use strict";
var exports;
exports.default = /** @class */ (function () {
    function default() {
        // do nothing
    }
    return default;
}());

Expected behavior:
The function name should be replaced when it might be invalid. In the above example, default is not a valid function name and function default() will throw an error in the browser.

[a-tarasyuk]

Duplicate of #26325

[RyanCavanaugh]

Thanks @a-tarasyuk