Simplify some code, reducing calls to MaskedValueIsZero.  Implement a minor optimization where we reduce the number of bits in AND masks when possible.
Simplify some code, reducing calls to MaskedValueIsZero.  Implement a minor
optimization where we reduce the number of bits in AND masks when possible.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@26056 91177308-0d34-0410-b5e6-96231b3b80d8

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