Revert "Re-add top-level v8::Locker"

The locker makes node crash in debug mode sometimes.
For example, test/simple/test-repl.js triggers it.

This reverts commit 9a6012edd9.

Conflicts:

	src/node.cc

src/node.cc

@@ -2759,15 +2759,12 @@ int Start(int argc, char *argv[]) {
   // Use copy here as to not modify the original argv:
   Init(argc, argv_copy);
 
-  V8::Initialize();
-  Persistent<Context> context;
-  {
-    Locker locker;
-    HandleScope handle_scope;
+  v8::V8::Initialize();
+  v8::HandleScope handle_scope;
 
   // Create the one and only Context.
-    Persistent<Context> context = Context::New();
-    Context::Scope context_scope(context);
+  Persistent<v8::Context> context = v8::Context::New();
+  v8::Context::Scope context_scope(context);
 
   // Use original argv, as we're just copying values out of it.
   Handle<Object> process_l = SetupProcessObject(argc, argv);
@@ -2785,13 +2782,10 @@ int Start(int argc, char *argv[]) {
   uv_run(uv_default_loop());
 
   EmitExit(process_l);
-#ifndef NDEBUG
-    context.Dispose();
-#endif
-  }
 
 #ifndef NDEBUG
   // Clean up.
+  context.Dispose();
   V8::Dispose();
 #endif  // NDEBUG