[TrimmableTypeMap] Pass TargetType and InvokerType through JavaPeerProxy constructor

[simonrozsival]

Problem

TargetType and InvokerType on generated proxy types were implemented as virtual property overrides. This had two issues:

1. Bug: get_InvokerType was emitted without MethodAttributes.Virtual, making it a new method. When accessed via the base JavaPeerProxy reference, the base returned null, preventing interface invoker types from being resolved.

2. Performance: Every access went through vtable dispatch for values that never change after construction.

Fix

Replace both virtual overrides with constructor parameters:

// JavaPeerProxy base — before:
public abstract Type TargetType { get; }
public virtual Type? InvokerType => null;

// JavaPeerProxy base — after:
public Type TargetType { get; }
public Type? InvokerType { get; }
protected JavaPeerProxy(Type targetType, Type? invokerType) { ... }

Generated proxy ctor: base(typeof(Activity), typeof(IActivityInvoker)) or base(typeof(Button), null).

JavaPeerProxy<T> updated to pass typeof(T) through base ctor instead of overriding TargetType.

Files changed

• JavaPeerProxy.cs — Single (Type, Type?) ctor; both properties are get-only fields; JavaPeerProxy<T> chains base(typeof(T), invokerType)
• TypeMapAssemblyEmitter.cs — Emit ldtoken TargetType + ldtoken InvokerType/ldnull + base(Type, Type?) in proxy ctor; remove get_TargetType and get_InvokerType overrides

[Copilot]

Pull request overview

Fixes trimmable typemap proxy generation so JavaPeerProxy.InvokerType is properly overridden on generated proxy types (instead of being emitted as a hidden new member), enabling runtime resolution of interface invoker types.

Changes:

• Emit get_InvokerType with MethodAttributes.Virtual to correctly override JavaPeerProxy.InvokerType.