Create frequently used symbols in the vm isolate

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"
 
 namespace dart {
 
 DEFINE_NATIVE_ENTRY(StringBase_createFromCodePoints, 1) {
   GET_NATIVE_ARGUMENT(Array, a, arguments->At(0));
   // TODO(srdjan): Check that parameterized type is an int.
   Zone* zone = Isolate::Current()->current_zone();
   intptr_t len = a.Length();
 
   // Unbox the array and determine the maximum element width.
@@ skipping 69 matching lines @@
     return 0;
   }
 }
 
 
 DEFINE_NATIVE_ENTRY(String_charAt, 2) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
   GET_NATIVE_ARGUMENT(Integer, index, arguments->At(1));
   uint32_t value = StringValueAt(receiver, index);
   ASSERT(value <= 0x10FFFF);
-  arguments->SetReturn(String::Handle(String::NewSymbol(&value, 1)));
+  arguments->SetReturn(String::Handle(Symbols::New(&value, 1)));
 }
 
 DEFINE_NATIVE_ENTRY(String_charCodeAt, 2) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
   GET_NATIVE_ARGUMENT(Integer, index, arguments->At(1));
   int32_t value = StringValueAt(receiver, index);
   ASSERT(value >= 0);
   ASSERT(value <= 0x10FFFF);
   arguments->SetReturn(Smi::Handle(Smi::New(value)));
 }
@@ skipping 38 matching lines @@
       GrowableArray<const Object*> args;
       args.Add(&elem);
       Exceptions::ThrowByType(Exceptions::kIllegalArgument, args);
     }
   }
   const String& result = String::Handle(String::ConcatAll(strings));
   arguments->SetReturn(result);
 }
 
 }  // namespace dart