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

runtime/vm/regexp_assembler_ir.cc

Index: runtime/vm/regexp_assembler_ir.cc
diff --git a/runtime/vm/regexp_assembler_ir.cc b/runtime/vm/regexp_assembler_ir.cc
index 7d4cff24286a1c8eeafa0ae8044e68622a93be2e..a41db4614d8dac6a5c265356f7683d8da921b56a 100644
--- a/runtime/vm/regexp_assembler_ir.cc
+++ b/runtime/vm/regexp_assembler_ir.cc
@@ -382,9 +382,8 @@ DEFINE_RAW_LEAF_RUNTIME_ENTRY(
 
 LocalVariable* IRRegExpMacroAssembler::Parameter(const String& name,
                                                  intptr_t index) const {
-  const Type& local_type = Type::ZoneHandle(Z, Type::DynamicType());
   LocalVariable* local =
-      new(Z) LocalVariable(kNoSourcePos, name, local_type);
+      new(Z) LocalVariable(kNoSourcePos, name, Object::dynamic_type());
 
   intptr_t param_frame_index = kParamEndSlotFromFp + kParamCount - index;
   local->set_index(param_frame_index);
@@ -394,9 +393,8 @@ LocalVariable* IRRegExpMacroAssembler::Parameter(const String& name,
 
 
 LocalVariable* IRRegExpMacroAssembler::Local(const String& name) {
-  const Type& local_type = Type::ZoneHandle(Z, Type::DynamicType());
   LocalVariable* local =
-      new(Z) LocalVariable(kNoSourcePos, name, local_type);
+      new(Z) LocalVariable(kNoSourcePos, name, Object::dynamic_type());
   local->set_index(GetNextLocalIndex());
 
   return local;