Fix running of CSS Animations in SVG-in-<img>/background-image/etc.

LayoutTests/svg/as-image/resources/css-animation.svg

Index: LayoutTests/svg/as-image/resources/css-animation.svg
diff --git a/LayoutTests/svg/as-image/resources/css-animation.svg b/LayoutTests/svg/as-image/resources/css-animation.svg
new file mode 100644
index 0000000000000000000000000000000000000000..9aec180ab1986101137fa84f28623387ebdbd2a4
--- /dev/null
+++ b/LayoutTests/svg/as-image/resources/css-animation.svg
@@ -0,0 +1,18 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">
+  <rect width="100" height="100" class="s0"/>
+  <style>
+  @keyframes pop { from { fill: red; } to { fill: green; } }
+  @-webkit-keyframes pop { from { fill: red; } to { fill: green; } }
+
+  .s0 {
+      animation-name: pop;
+      animation-duration: 0.001s;
+      animation-iteration-count: 1;
+      animation-fill-mode: forwards;
+      -webkit-animation-name: pop;
+      -webkit-animation-duration: 0.001s;
+      -webkit-animation-iteration-count: 1;
+      -webkit-animation-fill-mode: forwards;
+  }
+  </style>
+</svg>