The code was previously reading unsigned integers by performing an invalid cast
of Operator1<intNN_t> objects to Operator1<uintNN_t> and reading the integer
directly. To fix the invalid cast, we cast to the correct type and static_cast
the integer to uintNN_t, which is a no-op on every reasonable target.

Cleanup for cfi_vptr=1; see https://www.chromium.org/developers/testing/control-flow-integrity

BUG=chromium:457523
R=bmeurer@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1310633004

Cr-Commit-Position: refs/heads/master@{#30499}