Optimize functions on a second thread.

src/v8.cc

Index: src/v8.cc
diff --git a/src/v8.cc b/src/v8.cc
index 2910a0700d92223521dddf8a072fc65fb6fa9615..eaff43c9bfb4bb8bcd69b2c2fb52c8a00f0ebebe 100644
--- a/src/v8.cc
+++ b/src/v8.cc
@@ -106,13 +106,16 @@ void V8::TearDown() {
 
   if (!has_been_set_up_ || has_been_disposed_) 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;
+
   ElementsAccessor::TearDown();
   LOperand::TearDownCaches();
   RegisteredExtension::UnregisterAll();
 
-  isolate->TearDown();
-  delete isolate;
-
   is_running_ = false;
   has_been_disposed_ = true;