[wasm] Remove UseMonoRuntime=true from SDK

[maraf]

All the removed assignments are duplicates. We have the property set in WasmSDK at https://github.com/dotnet/sdk/blob/main/src/WasmSdk/Sdk/Sdk.props#L18

[dotnet-policy-service]

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[Copilot]

Pull request overview

This PR removes UseMonoRuntime=true property assignments from two WebAssembly SDK build files, claiming they are duplicates of a property set in the external dotnet/sdk WasmSDK repository.

• Removes unconditional UseMonoRuntime=true from WasmApp.Common.props
• Removes conditional UseMonoRuntime=true from Microsoft.NET.Runtime.WebAssembly.Sdk/Sdk/Sdk.props

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/mono/wasm/build/WasmApp.Common.props	Removes unconditional UseMonoRuntime=true assignment that applies to all projects using the WebAssembly SDK
src/mono/nuget/Microsoft.NET.Runtime.WebAssembly.Sdk/Sdk/Sdk.props	Removes conditional UseMonoRuntime=true assignment that only applies when NOT using external Blazor/WebAssembly SDKs

[Copilot]

Removing this conditional assignment may break scenarios where projects use Microsoft.NET.Sdk (not the WebAssembly SDK) with RuntimeIdentifier=browser-wasm.

The condition '$(UsingMicrosoftNETSdkBlazorWebAssembly)' != 'true' and '$(UsingMicrosoftNETSdkWebAssembly)' != 'true' specifically handles cases where the external dotnet/sdk WebAssembly or Blazor SDKs are NOT being used. For example, the console template at src/mono/wasm/templates/templates/console/console.0.csproj uses Microsoft.NET.Sdk with RuntimeIdentifier=browser-wasm, which would fall into this category.

If the external dotnet/sdk WasmSDK only sets UseMonoRuntime=true when UsingMicrosoftNETSdkWebAssembly is true, then removing both this conditional assignment and the unconditional one from WasmApp.Common.props would leave UseMonoRuntime unset for these scenarios.

Please verify that the external WasmSDK sets UseMonoRuntime=true for ALL scenarios where browser-wasm or wasi-wasm runtime identifiers are used, not just when using the Microsoft.NET.Sdk.WebAssembly SDK.

[Copilot]

Removing this unconditional assignment could break scenarios where UseMonoRuntime is not set by the external dotnet/sdk WasmSDK.

This file is imported via BrowserWasmApp.props → Sdk.targets and applies to all projects using Microsoft.NET.Runtime.WebAssembly.Sdk, including those that don't use Microsoft.NET.Sdk.WebAssembly or Microsoft.NET.Sdk.BlazorWebAssembly.

Before removing this, please confirm that:

1. The external WasmSDK sets UseMonoRuntime=true for projects with RuntimeIdentifier=browser-wasm regardless of which SDK they use
2. Or that Microsoft.NET.Runtime.WebAssembly.Sdk/Sdk/Sdk.props conditional assignment remains to cover non-WebAssembly-SDK scenarios

Since both assignments are being removed in this PR, there may be no fallback for projects that use Microsoft.NET.Sdk + wasm-tools workload instead of the WebAssembly SDK directly.