Remove duplicate test from LayoutTests/TestExpectations.

The following CLs added a NeedsRebaseline entry for
svg/filters/big-sized-filter.svg:
https://codereview.chromium.org/446593003
https://codereview.chromium.org/437673002

TBR=senorblanco@chromium.org,fmalita@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/443813002

git-svn-id: svn://svn.chromium.org/blink/trunk@179562 bbb929c8-8fbe-4397-9dbb-9b2b20218538