Use a reusable handle in SubString instead of creating one as this path is now used when creating S…

runtime/vm/object.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 "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 20032 matching lines @@
   if (begin_index >= str.Length()) {
     return String::null();
   }
   return String::SubString(str,
                            begin_index,
                            (str.Length() - begin_index),
                            space);
 }
 
 
-RawString* String::SubString(const String& str,
+RawString* String::SubString(Thread* thread,
+                             const String& str,
                              intptr_t begin_index,
                              intptr_t length,
                              Heap::Space space) {
   ASSERT(!str.IsNull());
   ASSERT(begin_index >= 0);
   ASSERT(length >= 0);
   if (begin_index <= str.Length() && length == 0) {
     return Symbols::Empty().raw();
   }
   if (begin_index > str.Length()) {
     return String::null();
   }
-  String& result = String::Handle();
   bool is_one_byte_string = true;
   intptr_t char_size = str.CharSize();
   if (char_size == kTwoByteChar) {
     for (intptr_t i = begin_index; i < begin_index + length; ++i) {
       if (!Utf::IsLatin1(str.CharAt(i))) {
         is_one_byte_string = false;
         break;
       }
     }
   }
+  REUSABLE_STRING_HANDLESCOPE(thread);
+  String& result = thread->StringHandle();
   if (is_one_byte_string) {
     result = OneByteString::New(length, space);
   } else {
     result = TwoByteString::New(length, space);
   }
   String::Copy(result, 0, str, begin_index, length);
   return result.raw();
 }
 
 
@@ skipping 2317 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart