WholeProgramDevirt: fix access to a non-initialized field.

Summary: This is a follow up to r278389, where I have introduced the bug

Reviewers: mehdi_amini

Differential Revision: https://reviews.llvm.org/D23436

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278442 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed