Convert all symbols accessor to return read only handles so that it is not necessary to create a ne…

vm/debugger_api_impl.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 "include/dart_debugger_api.h"
 
 #include "vm/dart_api_impl.h"
 #include "vm/dart_api_state.h"
 #include "vm/debugger.h"
 #include "vm/isolate.h"
@@ skipping 614 matching lines @@
     ASSERT(!imported.IsNull());
     ASSERT(Smi::IsValid(imported.index()));
     import_list.Add(Smi::Handle(Smi::New(imported.index())));
   }
   LibraryPrefixIterator it(lib);
   LibraryPrefix& prefix = LibraryPrefix::Handle(isolate);
   while (it.HasNext()) {
     prefix = it.GetNext();
     prefix_name = prefix.name();
     ASSERT(!prefix_name.IsNull());
-    prefix_name = String::Concat(prefix_name,
-                                 String::Handle(isolate, Symbols::Dot()));
+    prefix_name = String::Concat(prefix_name, Symbols::Dot());
     for (int i = 0; i < prefix.num_imports(); i++) {
       imported = prefix.GetLibrary(i);
       import_list.Add(prefix_name);
       import_list.Add(Smi::Handle(Smi::New(imported.index())));
     }
   }
   return Api::NewHandle(isolate, Array::MakeArray(import_list));
 }
 
 
@@ skipping 63 matching lines @@
   return Api::True(isolate);
 }
 
 
 DART_EXPORT Dart_Isolate Dart_GetIsolate(Dart_IsolateId isolate_id) {
   Isolate* isolate = PortMap::GetIsolate(isolate_id);
   return Api::CastIsolate(isolate);
 }
 
 }  // namespace dart