[EarlyCSE] Minor cosmetic NFC changes
[EarlyCSE] Minor cosmetic NFC changes

 - Avoid implicit conversion from pointer to bool
 - Add a comment when passing in a boolean value

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@272955 91177308-0d34-0410-b5e6-96231b3b80d8

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