[Bug] RegExp d Modifier

Reproducible in vscode.dev or in VS Code Desktop?

• Not reproducible in vscode.dev or VS Code Desktop

Reproducible in the monaco editor playground?

• Not reproducible in the monaco editor playground

Monaco Editor Playground Link

chrome version: 79
monaco-editor version:0.52.2

execute:
const markRegex = new RegExp('\bMARK:\s*(.*)$', 'd');
output:
Uncaught SyntaxError: Invalid flags supplied to RegExp constructor 'd'
at RegExp ()

Monaco Editor Playground Code

dev/vs/base/worker/workerMain.js:
 /*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
define(__m[67/*vs/editor/common/services/findSectionHeaders*/], __M([0/*require*/,1/*exports*/]), function (require, exports) {
    "use strict";
    Object.defineProperty(exports, "__esModule", { value: true });
    exports.findSectionHeaders = findSectionHeaders;
    const markRegex = new RegExp('\\bMARK:\\s*(.*)$', 'd');
    const trimDashesRegex = /^-+|-+$/g;

Reproduction Steps

No response

Actual (Problematic) Behavior

No response

Expected Behavior

No response

Additional Context

No response

Start with dev/vs/base/worker/workerMain.js and reproduce the RegExp constructor in the Monaco Editor Playground using monaco-editor 0.52.2 and Chrome 79. Investigate the reported SyntaxError for the d flag; done means the documented reproduction behaves as intended without that error.