UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.63 Safari/537.36

Steps to reproduce the problem:
1. Load a webpage and scroll part the way down
2. Middle click anywhere on the page
3. Scroll

What is the expected behavior?
The page scrolls from the current position

What went wrong?
The page scroll position abruptly jumps upwards, sometimes to the top of the page. The amount of the jump seems related to how far down the page I have scrolled.

Did this work before? Yes Chromium 49

Chrome version: 51.0.2704.63  Channel: stable
OS Version: Arch
Flash Version: Shockwave Flash 21.0 r0

I am using a laptop with a Synaptics touchpad, and I scroll by dragging along the right edge of the touch pad. I do not have a mouse to test if this happens with a regular mouse.