If you’re specifically looking for version 1.15.2, here is what you get to play with:
is an actual port of Minecraft 1.5.2 and 1.8.8 that runs in any browser using JavaScript/WebGL. unblocked games minecraft 15 2
Eaglercraft is the most prominent project in this niche. It is a JavaScript/HTML5 port that allows a full 1.5.2 experience directly in a web browser without requiring a Java installation on the host machine. If you’re specifically looking for version 1