UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.67 Safari/537.36

Steps to reproduce the problem:
Our framework Construct 3 has started using OffscreenCanvas. We discovered a memory leak involving uploading OffscreenCanvas to a WebGL texture. Our framework renders text in a WebGL game by first drawing text on a 2D canvas, uploading the canvas to a texture, and then drawing a quad with the texture. Switching the DOM canvas to an OffscreenCanvas, and inserting a call to transferToImageBitmap() (which used to be necessary since direct upload of OffscreenCanvas was not originally supported), results in endlessly increasing GPU memory until it kills the WebGL context.

To reproduce simply open the following URL, maximise the window (to reproduce quicker), and observe GPU memory in Chrome's task manager:

https://www.scirra.com/labs/bugs/gpumemleak/offscreencanvas/index.html

What is the expected behavior?
Compare to identical code but using DOM canvas instead:

https://www.scirra.com/labs/bugs/gpumemleak/domcanvas/index.html

This does not leak.

What went wrong?
The OffscreenCanvas version leaks GPU memory.

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 70.0.3538.67  Channel: stable
OS Version: 10.0
Flash Version: 

Removing the now-unnecessary call to transferToImageBitmap() also avoids the memory leak. However there should not be a memory leak even with the call to transferToImageBitmap().