Depth First Traversal of DOM Tree

# Introduction

In this challenge, we will tackle the task of performing a depth first traversal of a DOM tree. The goal is to create a function called `dfsDOMTree` that takes a DOM object as a parameter and returns an array containing all the tag names encountered during the traversal process. The function should follow the pre-order traversal method, where each branch is traversed from top to bottom before moving on to the next branch.