Build and run the attached project for WebGL. The browser will show the following error:

Uncaught abort(101) at Error
at jsStackTrace (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:1278:13)
at stackTrace (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:1295:22)
at abort (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:4042833:44)
at nullFunc_vii (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:15810:466)
at Array.b101 (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:4037545:45)
at _InputHandler_Invoke_m3001022841 (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:2339301:34)
at Array._CNJoystick_Update_m3065387993 (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:2339249:2)
at Array.__Z31RuntimeInvoker_Void_t2779279689PK10MethodInfoPvPS2_ [RuntimeInvoker_Void_t2779279689?2(void*, undefined?S?)] (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:3894724:32)
at __ZN6il2cpp2vm7Runtime6InvokeEPK10MethodInfoPvPS5_PP12Il2CppObject [il2cpp::vm::Runtime::Invoke?5(void*, undefined?S?)] (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:75990:38)
at _il2cpp_runtime_invoke (blob:http%3A//localhost%3A62954/75b5de1c-25a3-4d63-a980-d174ae44bbc4:33782:8)

Not a regression. Reproduced with Unity 5.2, Unity 5.3.2 and Unity 5.4.0b8