Treat final variables initialized with a literal as constants. Also sneak in a small cleanup.

runtime/lib/string.cc

 // Copyright (c) 2011, 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/bootstrap_natives.h"
 
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
@@ skipping 163 matching lines @@
 
 
 DEFINE_NATIVE_ENTRY(String_charAt, 2) {
   const String& receiver = String::CheckedHandle(arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(Integer, index, arguments->NativeArgAt(1));
   uint32_t value = StringValueAt(receiver, index);
   ASSERT(value <= 0x10FFFF);
   return Symbols::FromCharCode(value);
 }
 
+
 DEFINE_NATIVE_ENTRY(String_codeUnitAt, 2) {
   const String& receiver = String::CheckedHandle(arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(Integer, index, arguments->NativeArgAt(1));
 
   int32_t value = StringValueAt(receiver, index);
   ASSERT(value >= 0);
   ASSERT(value <= 0xFFFF);
   return Smi::New(value);
 }
 
@@ skipping 51 matching lines @@
       ? String::Handle(OneByteString::New(length_value, Heap::kNew))
       : String::Handle(TwoByteString::New(length_value, Heap::kNew));
   NoGCScope no_gc;
 
   uint16_t* data_position = reinterpret_cast<uint16_t*>(codeUnits.DataAddr(0));
   String::Copy(result, 0, data_position, length_value);
   return result.raw();
 }
 
 }  // namespace dart