To reproduce:
1. Open user's project, build and run (WebGL build)
2. While in running project click the screen few times to earn money
3. Close and open or refresh the browser tab, money is reset

Expected: money keeps on counting (OnApplicationQuit() saves PlayerPrefs)
Actual: money is reset to zero (OnApplicationQuit() doesn't execute thus not saving PlayerPrefs)

Reproduced in: 5.3.7p4 , 5.4.5p2, 5.5.3p3, 5.6.0p3, 5.6.0p4, 2017.1.0b3
Notes: tested on browsers: Google Chrome 57.0.2, Mozilla Firefox 53.0, Microsoft Edge 38.14

"Won't Fix" reason: "OnApplicationQuit()" in WebGL is not possible to implement due to nature of the browser tabs closing.
There's not enough time to trigger any additional events before closing happens.