Steps to reproduce:

1) Open Unity and create a new project
2) Switch platform to WebGL in Build Settings
3) Enable Development Build
4) In Player Settings, enable WebAssembly
5) Build and Run
6) After project launches, open browser's Console and wait around 3-15s
7) Observe Exception:
UnityLoader.js:234 exception thrown: RuntimeError: integer result unrepresentable,RuntimeError: integer result unrepresentable
at __ZN17DirectorFrameTime21CalculateDSPDeltaTimeEv (<WASM>[2471]+676)
at __ZN15DirectorManager12OnSampleTimeEv (<WASM>[2469]+139)
at __ZZN15DirectorManager15InitializeClassEvEN40EarlyUpdateDirectorSampleTimeRegistrator7ForwardEv (<WASM>[2445]+24)
at __Z10PlayerLoopv (<WASM>[2818]+918)
at __ZL8MainLoopv (<WASM>[2805]+247)
at dynCall_v (<WASM>[21568]+12)
at Object.UnityLoader.60dbf46e22b1026b583d08ed31d30926.Module.dynCall_v (blob:http://localhost:53312/0465e6fb-f33a-46f7-a4b2-616a2bf8c445:18352:86)
at browserIterationFunc (blob:http://localhost:53312/0465e6fb-f33a-46f7-a4b2-616a2bf8c445:2707:30)
at Object.runIter (blob:http://localhost:53312/0465e6fb-f33a-46f7-a4b2-616a2bf8c445:2824:13)
at Browser_mainLoop_runner (blob:http://localhost:53312/0465e6fb-f33a-46f7-a4b2-616a2bf8c445:2762:26)

Expected result: No exceptions or errors
Actual result: Exception been thrown after 3-15s

Reproduced with:
2017.1.0b2, 2017.1.0b6

Not reproduced with:
5.6.1p1, 2017.1.0b1

Regression since:
2017.1.0b2

Browser: Google Chrome, version 58.0.3029.110 (64-bit)

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Fixed in: 2017.1.0f1