[blinkpy] Re-enable two css-backgrounds/ tests now fuzzy reftests work

Bug: 997202
Change-Id: I45beb9e0ea3b0a905295e312664d010078306119
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2575452
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Auto-Submit: Stephen McGruer <smcgruer@chromium.org>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834236}

third_party/blink/web_tests/TestExpectations

@@ -374,11 +374,6 @@ crbug.com/997202 external/wpt/css/css-images/image-orientation/image-orientation
 crbug.com/997202 external/wpt/css/css-images/image-orientation/image-orientation-background-properties-border-radius.html [ Failure ]
 crbug.com/997202 external/wpt/density-size-correction/density-corrected-image-svg-aspect-ratio.html [ Failure ]
 
-# These have filtering antialiasing artifacts on one side only, but otherwise are passing. The tests
-# should be updated with the fuzzy meta data once enabled in the test driver.
-crbug.com/997202 external/wpt/css/css-backgrounds/border-image-slice-007.htm [ Failure ]
-crbug.com/997202 external/wpt/css/css-backgrounds/border-image-slice-005.htm [ Failure ]
-
 # Ref results are wrong on the background and list case, not sure on border result
 crbug.com/1076121 external/wpt/css/css-images/image-orientation/image-orientation-border-image.html [ Failure ]
 

third_party/blink/web_tests/external/wpt/css/css-backgrounds/border-image-slice-005.htm

@@ -11,6 +11,7 @@
         <link rel="help" href="http://www.w3.org/TR/css3-background/#the-border-image-slice">
         <link rel="match" href="reference/border-image-slice-005-ref.html">
         <meta name="flags" content="">
+        <meta name="fuzzy" content="0-35;0-1250">
         <meta name="assert" content="This test checks that the border image is sliced into nine regions with inward offsets, '40%' from the top, '30%' from the right,'20%' from the bottom, and '10%' from the left edges of the image. Percentages are relative to the size of the image: the width of the image for the horizontal offsets, the height for vertical offsets.">
         <style>
             div

third_party/blink/web_tests/external/wpt/css/css-backgrounds/border-image-slice-007.htm

@@ -11,6 +11,7 @@
         <link rel="help" href="http://www.w3.org/TR/css3-background/#the-border-image-slice">
         <link rel="match" href="reference/border-image-slice-007-ref.html">
         <meta name="flags" content="">
+        <meta name="fuzzy" content="0-35;0-1250">
         <meta name="assert" content="This test checks that the 'fill' keyword, if present, causes the middle part of the border-image to be preserved.">
         <style>
             div