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

runtime/vm/regexp.cc

Index: runtime/vm/regexp.cc
diff --git a/runtime/vm/regexp.cc b/runtime/vm/regexp.cc
index f58137c8e6efb7f1a392d0b9161f038c1487f3e9..46122bd9d3f02f94422415eac01819df5a442705 100644
--- a/runtime/vm/regexp.cc
+++ b/runtime/vm/regexp.cc
@@ -5276,15 +5276,15 @@ static void CreateSpecializedFunction(Zone* zone,
   fn.set_parameter_names(Array::Handle(zone, Array::New(kParamCount,
                                                            Heap::kOld)));
   fn.SetParameterTypeAt(RegExpMacroAssembler::kParamRegExpIndex,
-                        Type::Handle(zone, Type::DynamicType()));
+                        Object::dynamic_type());
   fn.SetParameterNameAt(RegExpMacroAssembler::kParamRegExpIndex,
                         Symbols::This());
   fn.SetParameterTypeAt(RegExpMacroAssembler::kParamStringIndex,
-                        Type::Handle(zone, Type::DynamicType()));
+                        Object::dynamic_type());
   fn.SetParameterNameAt(RegExpMacroAssembler::kParamStringIndex,
                         Symbols::string_param());
   fn.SetParameterTypeAt(RegExpMacroAssembler::kParamStartOffsetIndex,
-                        Type::Handle(zone, Type::DynamicType()));
+                        Object::dynamic_type());
   fn.SetParameterNameAt(RegExpMacroAssembler::kParamStartOffsetIndex,
                         Symbols::start_index_param());
   fn.set_result_type(Type::Handle(zone, Type::ArrayType()));