Basic support for (local) SVG <mask> references in 'mask-image'

This adds a new StyleImage subclass that allows producing an Image
from an SVGResource that points to a <mask> element.

Bug: 1369996
Change-Id: I8f2fece072562b19f199c17e303830d6da58152e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4955033
Reviewed-by: Traian Captan <tcaptan@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/main@{#1213498}
diff --git a/css/css-masking/mask-image/mask-image-3a.html b/css/css-masking/mask-image/mask-image-3a.html
index b3a6d39..3aae3df 100644
--- a/css/css-masking/mask-image/mask-image-3a.html
+++ b/css/css-masking/mask-image/mask-image-3a.html
@@ -8,6 +8,7 @@
     <link rel="help" href="https://www.w3.org/TR/css-masking-1/#the-mask-image">
     <link rel="match" href="mask-image-3-ref.html">
     <meta name="assert" content="Test checks whether SVG mask as mask layer works correctly or not.">
+    <meta name="fuzzy" content="0-1; 0-100">
     <svg height="0">
       <mask id="mask1" x="0" y="0" width="1" height="1" >
         <rect x="0" y="0" width="50" height="50" style="stroke:none; fill: #ffffff"/>