Add root verification when we try to mark an invalid object.

Now when we try to mark an object not contained by any spaces, We call verify
roots. This prints the root's vreg and method when it finds an invalid root.

Fixed a error in the total paused time statistic.

Change-Id: Id10e4097cce56bc54ee488de32183c18ba3f3780
diff --git a/src/thread_list.h b/src/thread_list.h
index 94e987f..3142fd3 100644
--- a/src/thread_list.h
+++ b/src/thread_list.h
@@ -81,6 +81,9 @@
   void VisitRoots(Heap::RootVisitor* visitor, void* arg) const
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
+  void VerifyRoots(Heap::VerifyRootVisitor* visitor, void* arg) const
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
   // Return a copy of the thread list.
   std::list<Thread*> GetList() EXCLUSIVE_LOCKS_REQUIRED(Locks::thread_list_lock_) {
     return list_;