Unused files

The following files in the optimizing compiler are
unused and contain errors. They don't get compiled as
part of any build, but they throw compile errors in
Eclipse. Can they be removed if they aren't necessary,
or at least get temporarily patched if deleting them
isn't desirable?

OPT_ComputeCriticalPath.java
OPT_DominatorTreePhase.java
OPT_PostDominatorsPhase.java
OPT_DF_Edge.java

Most of them only need a line or two changing, e.g.
adding an import or declaring abstract.