Remove freeing of zone allocate strings.

runtime/lib/isolate.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/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
@@ skipping 459 matching lines @@
   GET_NON_NULL_NATIVE_ARGUMENT(String, uri, arguments->NativeArgAt(0));
 
   // Canonicalize the uri with respect to the current isolate.
   char* error = NULL;
   char* canonical_uri = NULL;
   const Library& root_lib =
       Library::Handle(arguments->isolate()->object_store()->root_library());
   if (!CanonicalizeUri(arguments->isolate(), root_lib, uri,
                        &canonical_uri, &error)) {
     const String& msg = String::Handle(String::New(error));
-    free(error);
     ThrowIsolateSpawnException(msg);
   }
 
   return Spawn(arguments, new SpawnState(canonical_uri));
 }
 
 
 DEFINE_NATIVE_ENTRY(isolate_getPortInternal, 0) {
   const Object& port = Object::Handle(ReceivePortCreate(isolate->main_port()));
   if (port.IsError()) {
     Exceptions::PropagateError(Error::Cast(port));
   }
   return port.raw();
 }
 
 }  // namespace dart