Steps to reproduce:
1. Open the attached project(ProjetoTeste.rar)
2. Open the principal.unity scene
3. Go to Build Settings, switch platform to WebGL and click Build
4. Open created index.html
5. Hover your mouse pointer over the cube and click left button
6. Observe that the cube does not change the color (callbacks(OnPointerEnter and OnPointerDown) are not triggered)

Expected result: Cube should change the color on hover/click as the event is correctly received by the EventTrigger
Actual result: Cube does not change the color

Reproduced with: 5.5.0b5, 5.5.0b8
Not reproduced with: 5.4.1f1

Note:
- Tested on Chrome (Version 53.0.2785.143 m (64-bit))
- Tested on 49.0.1 (49.0.1)
- Tested on Microsoft Edge 25