feGaussian blur fails with large x,y ratio
the CIGaussianBlur filter only takes a radius, thus it fails for this. Other private filters fail due to not
supporting large ratios as the spec requires. It looks like we're either going to have to combine the
existing CIGuassianBlur filter with other filters to get the results we want, or have to write our own (or get
CI to fix theirs).
Testing this (using the w3c tests) is blocked on 5835 (as those tests require <use>).
This is an obscure test case, but we behave poorly on it. Ideally the CoreImage team will provide us with a better Guassian blur filter before we would choose to ship an SVG enabled WebKit.
Fix landed in r49402. Needs filters enabled build.