Disable syntax highlighting on unified views

Because we can't use background colors to denote added or removed
lines in the unified patch view, turn off syntax highlighting so
we can color the text of added lines green and deleted lines red.

Bug: issue 448
Change-Id: I994758b93e4f8b5633cd61c13911280c0bd7aafa
Signed-off-by: Shawn O. Pearce <sop@google.com>
3 files changed