Fix for issue 7089 (Symbols::New was not quite working correctly

vm/dart_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_api.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart.h"
@@ skipping 1544 matching lines @@
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   if (utf8_array == NULL && length != 0) {
     RETURN_NULL_ERROR(utf8_array);
   }
   CHECK_LENGTH(length, String::kMaxElements);
   if (!Utf8::IsValid(utf8_array, length)) {
     return Api::NewError("%s expects argument 'str' to be valid UTF-8.",
                          CURRENT_FUNC);
   }
-  return Api::NewHandle(isolate, String::New(utf8_array, length));
+  return Api::NewHandle(isolate, String::FromUTF8(utf8_array, length));
 }
 
 
 DART_EXPORT Dart_Handle Dart_NewStringFromUTF16(const uint16_t* utf16_array,
                                                 intptr_t length) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   if (utf16_array == NULL && length != 0) {
     RETURN_NULL_ERROR(utf16_array);
   }
@@ skipping 2877 matching lines @@
   }
   {
     NoGCScope no_gc;
     RawObject* raw_obj = obj.raw();
     isolate->heap()->SetPeer(raw_obj, peer);
   }
   return Api::Success(isolate);
 }
 
 }  // namespace dart