Add Genericity enum in VM to distinguish how a type is uninstantiated.

runtime/vm/constant_propagator.cc

Index: runtime/vm/constant_propagator.cc
diff --git a/runtime/vm/constant_propagator.cc b/runtime/vm/constant_propagator.cc
index f3827b0ee97043226e98e417ad52aa088f71ceb5..a147466267323efa4505354f13cb7b5e16fd255f 100644
--- a/runtime/vm/constant_propagator.cc
+++ b/runtime/vm/constant_propagator.cc
@@ -859,7 +859,9 @@ void ConstantPropagator::VisitLoadField(LoadFieldInstr* instr) {
 
 
 void ConstantPropagator::VisitInstantiateType(InstantiateTypeInstr* instr) {
-  const Object& object = instr->instantiator()->definition()->constant_value();
+  const Object& object =
+      instr->instantiator_type_arguments()->definition()->constant_value();
+  // TODO(regis): Check function type arguments.
   if (IsNonConstant(object)) {
     SetValue(instr, non_constant_);
     return;
@@ -880,7 +882,9 @@ void ConstantPropagator::VisitInstantiateType(InstantiateTypeInstr* instr) {
 
 void ConstantPropagator::VisitInstantiateTypeArguments(
     InstantiateTypeArgumentsInstr* instr) {
-  const Object& object = instr->instantiator()->definition()->constant_value();
+  const Object& object =
+      instr->instantiator_type_arguments()->definition()->constant_value();
+  // TODO(regis): Check function type arguments.
   if (IsNonConstant(object)) {
     SetValue(instr, non_constant_);
     return;