Use the tonic namespace for tonic + resulting build fixes

tonic/dart_builtin.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_builtin.h"
 
 #include <stdlib.h>
 #include <string.h>
 
 #include "base/logging.h"
 #include "tonic/dart_converter.h"
 
-namespace blink {
+namespace tonic {
 
 DartBuiltin::DartBuiltin(const Natives* natives, size_t count)
     : natives_(natives), count_(count) {
 }
 
 DartBuiltin::~DartBuiltin() {
 }
 
 Dart_NativeFunction DartBuiltin::Resolver(Dart_Handle name,
                                           int argument_count,
@@ skipping 22 matching lines @@
   }
   return nullptr;
 }
 
 Dart_Handle DartBuiltin::LookupLibrary(const char* name) {
     Dart_Handle library = Dart_LookupLibrary(ToDart(name));
     DCHECK(!Dart_IsError(library));
     return library;
 }
 
-}  // namespace blink
+}  // namespace tonic