Simplify timeline backend

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 33048344a5e8c83ce2d408c8f812f2d10bf6e5ec..f3854bc64110515b28b523e4f17142bcd651b8a9 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -1616,7 +1616,7 @@ void Isolate::LowLevelShutdown() {
   set_message_handler(NULL);
 
   // Before analyzing the isolate's timeline blocks- reclaim all cached blocks.
-  ReclaimTimelineBlocks();
+  Timeline::ReclaimCachedBlocksFromThreads();
 
   // Dump all timing data for the isolate.
   if (FLAG_timing) {
@@ -1718,15 +1718,6 @@ void Isolate::Shutdown() {
 }
 
 
-void Isolate::ReclaimTimelineBlocks() {
-  TimelineEventRecorder* recorder = Timeline::recorder();
-  if (recorder == NULL) {
-    return;
-  }
-  thread_registry_->ReclaimTimelineBlocks();
-}
-
-
 Dart_IsolateCreateCallback Isolate::create_callback_ = NULL;
 Dart_IsolateInterruptCallback Isolate::interrupt_callback_ = NULL;
 Dart_IsolateUnhandledExceptionCallback