Fix zygote live/mark bitmap size.

Fixed some errors with the sizes of mark/live bitmaps after zygote space creation.

This was causing us to occasionally have overlapping mark/live bitmaps.

Added a new verify objects mode called VERIFY_OBJECT_FAST which only checks objects and not their classes.

Refactored/optimized some of the scanning code to use xor to clear bits instead of and+not.

Change-Id: Iec87d9157f69e6a558e300950b51d8781679e3f7
diff --git a/src/heap.h b/src/heap.h
index a1b1bd9..e908248 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -31,6 +31,9 @@
 
 #define VERIFY_OBJECT_ENABLED 0
 
+// Fast verification means we do not verify the classes of objects.
+#define VERIFY_OBJECT_FAST 1
+
 namespace art {
 
 class AllocSpace;