[RuntimeAsync] Remove reflection TODOs. Add tests.

src/coreclr/vm/commodule.cpp

@@ -295,19 +295,10 @@ extern "C" INT32 QCALLTYPE ModuleBuilder_GetMemberRefOfMethodInfo(QCall::ModuleH
     if (!pMeth)
         COMPlusThrow(kArgumentNullException);
 
-    // Otherwise, we want to return memberref token.
-    if (pMeth->IsArray())
-    {
-        _ASSERTE(!"Should not have come here!");
-        COMPlusThrow(kNotSupportedException);
-    }
-
-    // TODO: (async) revisit and examine if this needs to be supported somehow
-    if (pMeth->IsAsyncVariantMethod())
-    {
-        _ASSERTE(!"Async variants should be hidden from reflection.");
-        COMPlusThrow(kNotSupportedException);
-    }
+    // Should not have come here.
+    _ASSERTE(!pMeth->IsArray());
+    // Async variants should be hidden from reflection.
+    _ASSERTE(!pMeth->IsAsyncVariantMethod());
 
     if ((pMeth->GetMethodTable()->GetModule() == pModule))
     {

src/coreclr/vm/runtimehandles.cpp

@@ -1863,8 +1863,7 @@ extern "C" void QCALLTYPE RuntimeMethodHandle_StripMethodInstantiation(MethodDes
 //          async variants for task-returning methods
 //
 // For {task-returning, async} variants Reflection hands out only the task-returning variant.
-//  the async varinat is an implementation detail that conceptually does not exist.
-//  TODO: (async) the filtering may not cover all scenarios. Review and add tests.
+//  the async variant is an implementation detail that conceptually does not exist.
 //
 // For generic methods we always hand out an instantiating stub except for a generic method definition
 // For non-generic methods on generic types we need an instantiating stub if it's one of the following