Add --timeline-recorder= flag and fix --timeline-dir flag

runtime/vm/log.cc

 // Copyright (c) 2015, 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 "vm/log.h"
 
 #include "vm/flags.h"
 #include "vm/thread.h"
 
 namespace dart {
@@ skipping 13 matching lines @@
 
 
 Log::~Log() {
   // Did someone enable manual flushing and then forgot to Flush?
   ASSERT(cursor() == 0);
 }
 
 
 Log* Log::Current() {
   Thread* thread = Thread::Current();
+  if (thread == NULL) {
+    OSThread* os_thread = OSThread::Current();
+    ASSERT(os_thread != NULL);
+    return os_thread->log();
+  }
   Isolate* isolate = thread->isolate();
   if (isolate != NULL && Log::ShouldLogForIsolate(isolate)) {
     OSThread* os_thread = thread->os_thread();
     ASSERT(os_thread != NULL);
     return os_thread->log();
   } else {
     return Log::NoOpLog();
   }
 }
 
@@ skipping 129 matching lines @@
   log_->EnableManualFlush();
 }
 
 
 LogBlock::~LogBlock() {
   log_->Flush(cursor_);
   log_->DisableManualFlush();
 }
 
 }  // namespace dart