More X86 fixes.

Fix bugs in a few long entrypoints and with object validation being
enabled.

Change-Id: I18884fbbe6829b584b9fc92e338549577f925f14
diff --git a/src/heap.cc b/src/heap.cc
index d2aada4..8a7ab3d 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -313,6 +313,7 @@
 #if VERIFY_OBJECT_ENABLED
 void Heap::VerifyObject(const Object* obj) {
   if (this == NULL || !verify_objects_ || Runtime::Current()->IsShuttingDown() ||
+      Thread::Current() == NULL ||
       Runtime::Current()->GetThreadList()->GetLockOwner() == Thread::Current()->GetTid()) {
     return;
   }