VM: Use read-only handle Object::dynamic_type() where possible.

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 60c20aef02aab97163b42f040aa00daa82cb9f38..23b39b682930cf60cc57332d0c6aea2d015e0568 100644
--- a/runtime/vm/flow_graph_type_propagator.cc
+++ b/runtime/vm/flow_graph_type_propagator.cc
@@ -413,7 +413,7 @@ void CompileType::Union(CompileType* other) {
   // Nothing to do.
   } else {
   // Can't unify.
-  type_ = &Type::ZoneHandle(Type::DynamicType());
+  type_ = &Object::dynamic_type();
   }
 }
 
@@ -441,7 +441,7 @@ CompileType CompileType::FromCid(intptr_t cid) {
 
 
 CompileType CompileType::Dynamic() {
-  return Create(kDynamicCid, Type::ZoneHandle(Type::DynamicType()));
+  return Create(kDynamicCid, Object::dynamic_type());
 }
 
 
@@ -534,14 +534,14 @@ const AbstractType* CompileType::ToAbstractType() {
   if (type_ == NULL) {
     // Type propagation has not run. Return dynamic-type.
     if (cid_ == kIllegalCid) {
-      type_ = &Type::ZoneHandle(Type::DynamicType());
+      type_ = &Object::dynamic_type();
       return type_;
     }
 
     // VM-internal objects don't have a compile-type. Return dynamic-type
     // in this case.
     if (cid_ < kInstanceCid) {
-      type_ = &Type::ZoneHandle(Type::DynamicType());
+      type_ = &Object::dynamic_type();
       return type_;
     }
 
@@ -549,7 +549,7 @@ const AbstractType* CompileType::ToAbstractType() {
         Class::Handle(Isolate::Current()->class_table()->At(cid_));
 
     if (type_class.NumTypeArguments() > 0) {
-      type_ = &Type::ZoneHandle(Type::DynamicType());
+      type_ = &Object::dynamic_type();
       return type_;
     }
 
@@ -859,28 +859,28 @@ CompileType RelationalOpInstr::ComputeType() const {
 CompileType CurrentContextInstr::ComputeType() const {
   return CompileType(CompileType::kNonNullable,
                      kContextCid,
-                     &AbstractType::ZoneHandle(Type::DynamicType()));
+                     &Object::dynamic_type());
 }
 
 
 CompileType CloneContextInstr::ComputeType() const {
   return CompileType(CompileType::kNonNullable,
                      kContextCid,
-                     &AbstractType::ZoneHandle(Type::DynamicType()));
+                     &Object::dynamic_type());
 }
 
 
 CompileType AllocateContextInstr::ComputeType() const {
   return CompileType(CompileType::kNonNullable,
                      kContextCid,
-                     &AbstractType::ZoneHandle(Type::DynamicType()));
+                     &Object::dynamic_type());
 }
 
 
 CompileType AllocateUninitializedContextInstr::ComputeType() const {
   return CompileType(CompileType::kNonNullable,
                      kContextCid,
-                     &AbstractType::ZoneHandle(Type::DynamicType()));
+                     &Object::dynamic_type());
 }