position-relative-035 reftest -> expected fail

There is no easy way to pass position-relative-035 & also
pass both tests/ref/border_rounding_1px_invisible_issue_7184 and
tests/ref/text_decoration_underline_subpx.

#7161, "Snap rectangles to nearest
pixels...", did fix position-relative-035 (except
for OS X) but broke 1px borders.

tests/wpt/metadata-css/css21_dev/html4/position-relative-035.htm.ini

@@ -1,4 +1,3 @@
 [position-relative-035.htm]
   type: reftest
-  expected:
-    if os == "mac": FAIL
+  expected: FAIL