Fix diff generation by difflib to report missing end of file newlines.

Tools/Scripts/webkitpy/layout_tests/port/base.py

Index: Tools/Scripts/webkitpy/layout_tests/port/base.py
diff --git a/Tools/Scripts/webkitpy/layout_tests/port/base.py b/Tools/Scripts/webkitpy/layout_tests/port/base.py
index ab4f31acfa96af84e8ec202d247abb9a60805545..2f27e8ebb0efeba0dcf73e96902dd2e19f7aa83a 100644
--- a/Tools/Scripts/webkitpy/layout_tests/port/base.py
+++ b/Tools/Scripts/webkitpy/layout_tests/port/base.py
@@ -526,7 +526,17 @@ class Port(object):
                                     actual_text.splitlines(True),
                                     expected_filename,
                                     actual_filename)
-        return ''.join(diff)
+
+        # The diff generated by the difflib is incorrect if one of the files
+        # does not have a newline at the end of the file and it is present in
+        # the diff. Relevant Python issue: http://bugs.python.org/issue2142
+        def diff_fixup(diff):
+            for line in diff:
+                yield line
+                if not line.endswith('\n'):
+                    yield '\n\ No newline at end of file\n'
+
+        return ''.join(diff_fixup(diff))
 
     def driver_name(self):
         if self.get_option('driver_name'):