Constify the 'dump' method so that it can be called by a const object.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182620 91177308-0d34-0410-b5e6-96231b3b80d8
Fix crash-on-invalid if list-initialization works, but we bail out when
building the resulting expression because it invokes a deleted constructor.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182624 91177308-0d34-0410-b5e6-96231b3b80d8