Reproduction Steps:
1. Import project "WebAssembly".
2. Open scene "gMain".
3. In Player Settings, make sure "WebAssembly (Experimental)" is enabled.
4. Build and Run WebGL build with the current scene. (Development Build enabled)
5. Play build in a web browser.

Expected result: Scene is played, similar to a regular WebGL build.
Actual result: Browser gives out error "An error occurred running the Unity content on this page. See your browser JavaScript console for more info. The error was:
RuntimeError: integer overflow". (Call stack can be viewed in browser Inspector).

Reproducible with: 2017.1.0b6

Note #1: Even though the same scene does not give out an error if it's a WebGL build, it does not load the AssetBundle as it does in the Editor. This is also true if it's a Standalone Build.

Note #2: The project also has a script that loads a scene from an Asset Bundle. This is achieved by using AssetBundle.LoadFromFile and SceneManager.LoadScene. However, the scene seems to be broken and might be the reason why the script doesn't work in Standalone and WebGL Builds. (An image of the scene is attached)

Note #3: The Asset Bundle is created through a custom plugin. You can create the Asset Bundle following these reproduction steps:
1. Import project "AssetBundle"
2. Open scene "room_classic".
3. Switch platform to WebGL.
4. In the Menu, select "Windpw" -> "ContentIntegrator" -> "Assets" -> "AssetBundleNames".
5. Select "Export Asset Bundles".