To reproduce:
1. Open the "Transparenttest2" scene in the attached project
2. Select CameraSystem\Main Camera from the Hierarchy
3. In the Inspector, make sure that "Post Processing Behaviour" script component is enabled
4. Build on WebGL
5. Launch build from local server

Desired outcome: Build loads and Game Objects are visible.
Actual result: Build loads to a black blank screen.

Note: Build loads correctly when "Post Processing Behaviour" (step 3) is disabled.

Reproduced with 5.6.0b11, 5.6.1f1, 5.6.2p1, 2017.1.0b10, 2017.1.0f2, 2017.2.0b1
Could not reproduce on 5.5 due to errors.

Tested with:
Apple Safari: Version 10.1.1 (12603.2.1)
Mozilla Firefox: 54.0.1 (build 20170628075643)
Google Chrome: Version 58.0.3029.110 (64-bit)