Add class flags to class to help GC scanning

Add class flags to class to help GC scanning

Reduces GC time and pauses by reducing the number of loads required
to scan an object.

Average total GC time before on EvaluateAndApplyChanges (EAAC): 7.452s
After: 7.144s

Average GC pause times before on EAAC: 860.67us
After: 722.75us

Adding the class flags field cause a memory increase of ~24k system
wide on low memory devices.

Change-Id: I3f04212d5787bfbf5e55026584d149f55476105e