PLEASE PROVIDE PROPER HTML5 SUPPORT

[half-moon]

Off-topic:
Don't mention http://html5test.com , you make me remember the troll user: www.com

As the result of http://html5test.com, what Firefox 53 has, but Pale Moon 27 not:
Speech Synthesis
DRM
Gamepad control
WebGL 2
Web Animations API
Service Workers
Push API
Fetch API
WebRTC and related
Webcam
Async and Await (ECMAScript 7)
Classes (ECMAScript 6)
Subresource Integrity


Well, these features are cool but useless.
Read this as the standard answer:

Pale Moon - General Information
Pale Moon is a middle road, cutting away support for particularly old hardware and operating systems to achieve a significant speed and efficiency increase, but not trying to squeeze the last few percent more out of it by limiting the range of systems it will run on even more. Pale Moon aims to deliver above all a stable and smooth browsing experience, and does not intend to or aim for high scoring in synthetic tests, as those are invariably not a good representation of typical use of a web browser in the real world.

DRM is certainly not a cool feature.

[dark_moon]

Same like WebRTC