Revert r298815: Do not use assert to report broken input files.
Revert r298815: Do not use assert to report broken input files.

This reverts commit because this really shouldn't happen unless
there's a bug in LLD.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@299021 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld