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/space_test.cc b/src/space_test.cc
index f377a61..c1c1dca 100644
--- a/src/space_test.cc
+++ b/src/space_test.cc
@@ -70,6 +70,10 @@
   }
 }
 
+// TODO: This test is not very good, we should improve it.
+// The test should do more allocations before the creation of the ZygoteSpace, and then do
+// allocations after the ZygoteSpace is created. The test should also do some GCs to ensure that
+// the GC works with the ZygoteSpace.
 TEST_F(SpaceTest, ZygoteSpace) {
     AllocSpace* space(Space::CreateAllocSpace("test", 4 * MB, 16 * MB, 16 * MB, NULL));
     ASSERT_TRUE(space != NULL);