Fix another edge case for "function call should be type cast" linter rule

Summary: Fix a minor issue in which changing a function call to a type cast affects the result of an expression.

Test Plan: Added test case.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D14623