Create read only handles for empty_array and sentinel objects

lib/array.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 #include "vm/bootstrap_natives.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
@@ skipping 56 matching lines @@
 
 // ObjectArray src, int srcStart, int dstStart, int count.
 DEFINE_NATIVE_ENTRY(ObjectArray_copyFromObjectArray, 5) {
   const Array& dest = Array::CheckedHandle(arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(Array, source, arguments->NativeArgAt(1));
   GET_NON_NULL_NATIVE_ARGUMENT(Smi, src_start, arguments->NativeArgAt(2));
   GET_NON_NULL_NATIVE_ARGUMENT(Smi, dst_start, arguments->NativeArgAt(3));
   GET_NON_NULL_NATIVE_ARGUMENT(Smi, count, arguments->NativeArgAt(4));
   intptr_t icount = count.Value();
   if (icount < 0) {
-    const Array& args = Array::Handle(Object::empty_array());
-    Exceptions::ThrowByType(Exceptions::kArgument, args);
+    Exceptions::ThrowByType(Exceptions::kArgument, Object::empty_array());
   }
   if (icount == 0) {
     return Object::null();
   }
   intptr_t isrc_start = src_start.Value();
   intptr_t idst_start = dst_start.Value();
   if ((isrc_start < 0) || ((isrc_start + icount) > source.Length())) {
     const Array& args = Array::Handle(Array::New(1));
     args.SetAt(0, src_start);
     Exceptions::ThrowByType(Exceptions::kRange, args);
@@ skipping 13 matching lines @@
   } else {
     for (intptr_t i = 0; i < icount; i++) {
       src_obj = source.At(isrc_start + i);
       dest.SetAt(idst_start + i, src_obj);
     }
   }
   return Object::null();
 }
 
 }  // namespace dart