Default the timezone to UTC if it is not resolved.

Browsers may not correctly resolve the machine's timezone in some cases. In the current implementation,
this results in an exception being thrown by .NET Core (WASM). This code defaults the timezone to UTC
when the timezone cannot be resolved.

Fixes dotnet/runtime#44154
Port of #27444

Author: pranavkm

src/Components/Web.JS/dist/Release/blazor.server.js

@@ -425,7 +425,7 @@ function createEmscriptenModuleInstance(resourceLoader: WebAssemblyResourceLoade
     try {
       timeZone = Intl.DateTimeFormat().resolvedOptions().timeZone;
     } catch { }
-    MONO.mono_wasm_setenv("TZ", timeZone);
+    MONO.mono_wasm_setenv("TZ", timeZone || 'UTC');
     // Turn off full-gc to prevent browser freezing.
     const mono_wasm_enable_on_demand_gc = cwrap('mono_wasm_enable_on_demand_gc', null, ['number']);
     mono_wasm_enable_on_demand_gc(0);