Use off-heap data for class check instructions

runtime/vm/flow_graph_type_propagator.cc

Index: runtime/vm/flow_graph_type_propagator.cc
diff --git a/runtime/vm/flow_graph_type_propagator.cc b/runtime/vm/flow_graph_type_propagator.cc
index 9617c03b3480e0c38da4ba21e4a48e71c1708757..43a8458996f978a7bd75ed31a91053e907c1e4e2 100644
--- a/runtime/vm/flow_graph_type_propagator.cc
+++ b/runtime/vm/flow_graph_type_propagator.cc
@@ -226,15 +226,17 @@ void FlowGraphTypePropagator::VisitCheckArrayBound(
 
 
 void FlowGraphTypePropagator::VisitCheckClass(CheckClassInstr* check) {
-  if (!check->unary_checks().NumberOfChecksIs(1) ||
-      !check->Dependencies().IsNone()) {
+  if (!check->cids().IsMonomorphic()) {
+    return;
+  }
+
+  if (!check->Dependencies().IsNone()) {
     // TODO(vegorov): If check is affected by side-effect we can still propagate
     // the type further but not the cid.
     return;
   }
 
-  SetCid(check->value()->definition(),
-         check->unary_checks().GetReceiverClassIdAt(0));
+  SetCid(check->value()->definition(), check->cids().MonomorphicReceiverCid());
 }
 
 
@@ -473,7 +475,7 @@ void FlowGraphTypePropagator::StrengthenAssertWith(Instruction* check) {
     ASSERT(check->IsCheckClass());
     check_clone = new CheckClassInstr(
         assert->value()->Copy(zone()), assert->env()->deopt_id(),
-        check->AsCheckClass()->unary_checks(), check->token_pos());
+        check->AsCheckClass()->cids(), check->token_pos());
     check_clone->AsCheckClass()->set_licm_hoisted(
         check->AsCheckClass()->licm_hoisted());
   }
@@ -1025,7 +1027,7 @@ CompileType AllocateUninitializedContextInstr::ComputeType() const {
 
 CompileType PolymorphicInstanceCallInstr::ComputeType() const {
   if (!IsSureToCallSingleRecognizedTarget()) return CompileType::Dynamic();
-  const Function& target = *targets_[0].target;
+  const Function& target = *targets_.TargetAt(0)->target;
   return (target.recognized_kind() != MethodRecognizer::kUnknown)
              ? CompileType::FromCid(MethodRecognizer::ResultCid(target))
              : CompileType::Dynamic();