Simplify v8/Isolate teardown.

src/v8.cc

Index: src/v8.cc
diff --git a/src/v8.cc b/src/v8.cc
index afe8e4b0551bafe9e2338150109aa3836ee6737e..ed328457c456d71575caca2cbdf885905477654a 100644
--- a/src/v8.cc
+++ b/src/v8.cc
@@ -77,16 +77,6 @@ bool V8::Initialize(Deserializer* des) {
 
 
 void V8::TearDown() {
-  Isolate* isolate = Isolate::Current();
-  ASSERT(isolate->IsDefaultIsolate());
-  if (!isolate->IsInitialized()) return;
-
-  // The isolate has to be torn down before clearing the LOperand
-  // caches so that the optimizing compiler thread (if running)
-  // doesn't see an inconsistent view of the lithium instructions.
-  isolate->TearDown();
-  delete isolate;
-
   Bootstrapper::TearDownExtensions();
   ElementsAccessor::TearDown();
   LOperand::TearDownCaches();
@@ -98,7 +88,6 @@ void V8::TearDown() {
   call_completed_callbacks_ = NULL;
 
   Sampler::TearDown();
-  Serializer::TearDown();
 
 #ifdef V8_USE_DEFAULT_PLATFORM
   DefaultPlatform* platform = static_cast<DefaultPlatform*>(platform_);