Use the tonic namespace for tonic + resulting build fixes

tonic/dart_error.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tonic/dart_error.h"
 
 #include "base/logging.h"
 
-namespace blink {
+namespace tonic {
 
 namespace DartError {
 
 const char kInvalidArgument[] = "Invalid argument.";
 
 }  // namespace DartError
 
 bool LogIfError(Dart_Handle handle) {
   if (Dart_IsError(handle)) {
     LOG(ERROR) << Dart_GetError(handle);
 
     // Only unhandled exceptions have stacktraces.
     if (!Dart_ErrorHasException(handle))
       return true;
 
     Dart_Handle stacktrace = Dart_ErrorGetStacktrace(handle);
     const char* stacktrace_cstr = "";
     Dart_StringToCString(Dart_ToString(stacktrace), &stacktrace_cstr);
     LOG(ERROR) << stacktrace_cstr;
     return true;
   }
   return false;
 }
 
-}  // namespace blink
+}  // namespace tonic