Remove operator[] that was used only in tests.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@208020 91177308-0d34-0410-b5e6-96231b3b80d8
Fix spelling.

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@208022 91177308-0d34-0410-b5e6-96231b3b80d8