Fixes for type descriptor with generics (#3220)

***NO_CI***

Author: josesimoes

src/CLR/Core/CLR_RT_HeapBlock.cpp

@@ -791,7 +791,7 @@ bool CLR_RT_HeapBlock::TypeDescriptorsMatch(
 
     // If the *actual* object is a closed-generic (even though boxed as CLASS),
     // it will have m_handlerGenericType set.  Promote it to GENERICINST.
-    if (actualDataType == DATATYPE_CLASS && actualType.m_handlerGenericType.data != CLR_EmptyToken)
+    if (actualDataType == DATATYPE_CLASS && NANOCLR_INDEX_IS_VALID(actualType.m_handlerGenericType))
     {
         actualDataType = DATATYPE_GENERICINST;
     }

src/CLR/Core/TypeSystem.cpp

@@ -2269,7 +2269,9 @@ HRESULT CLR_RT_TypeDescriptor::InitializeFromSignatureToken(
                 // !T: ask the CLR to map that slot into the *actual* argument
                 CLR_RT_TypeDef_Index td;
                 NanoCLRDataType dt;
-                assm->FindGenericParamAtTypeSpec(caller->genericType->data, elem.GenericParamPosition, td, dt);
+
+                g_CLR_RT_TypeSystem.m_assemblies[caller->genericType->Assembly() - 1]
+                    ->FindGenericParamAtTypeSpec(caller->genericType->data, elem.GenericParamPosition, td, dt);
                 this->InitializeFromTypeDef(td);
             }
             else if (elem.DataType == DATATYPE_MVAR)