TransformDisplayClassUsage: Support methods without .locals init

[yyjdelete]

Tested with master(6.0.0.5337-alpha1)

I don't have an minimum reproduce with C# code, but can be tested with Assemblies from netcoreapp3.0. Seems need an method without .locals init, and variable.HasInitialValue is false here.

ILSpy/ICSharpCode.Decompiler/IL/Transforms/TransformDisplayClassUsage.cs

Line 125 in 9bb2ea8

if (context.Settings.LocalFunctions && closureType?.Kind == TypeKind.Struct && variable.HasInitialValue && IsPotentialClosure(this.context, closureType)) {

[System.Linq]System.Collections.Generic.LargeArrayBuilder<T>.CopyTo(CopyPosition position, T[] array, int arrayIndex, int count)(netcoreapp3.0)
and
[System.Text.Json]System.Text.Json.JsonNode.Parse(...)(netcoreapp5.0 ONLY)

[siegfriedpammer]

Seems like in .NET 5.0 C# will no longer emit .locals init by default.