Revert "Clean up interface to ProgramImpl::link." Probably causing bot failures in a prior dependent patch. BUG=angleproject:1123 This reverts commit b83592750d00ca96413575016b0e27bc9d861f58. Change-Id: I7642c4a66b190dda49cbb16611abc893f3eb6422 Reviewed-on: https://chromium-review.googlesource.com/296700 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>