Revert of [SVG] Implement 'discard' element

LayoutTests/svg/animations/discard-check-delete.svg

Index: LayoutTests/svg/animations/discard-check-delete.svg
diff --git a/LayoutTests/svg/animations/discard-check-delete.svg b/LayoutTests/svg/animations/discard-check-delete.svg
deleted file mode 100644
index 932d3ec8eb6bc60dba3c6ecc8dd7148e699f16b9..0000000000000000000000000000000000000000
--- a/LayoutTests/svg/animations/discard-check-delete.svg
+++ /dev/null
@@ -1,28 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<svg onload="loaded()" version="1.2" baseProfile="tiny" id="svg-root" width="100%" height="100%"
-  viewBox="0 0 480 360" xmlns="http://www.w3.org/2000/svg"
-  xmlns:xlink="http://www.w3.org/1999/xlink">
-  <rect id="r1" x="100" y="100" width="200" height="200" fill="green"/>
-  <rect id="r2" x="100" y="100" width="200" height="200" fill="red" />
-  <discard id="discard1" xlink:href="#r2" begin="2s"/>
-  <set id="set" attributeName="display" to="inline" begin="3s" dur="1s" fill="freeze" onbegin="test();"/>
-  <script>
-    if (window.testRunner)
-      testRunner.waitUntilDone();
-
-    function loaded() {
-      document.documentElement.setCurrentTime(4);
-
-      if (window.testRunner)
-        setTimeout(function(){testRunner.notifyDone();}, 10);
-    }
-
-    function test() {
-      var d1 = document.getElementById("discard1");
-      var r2 = document.getElementById("r2");
-
-      if(d1 || r2)
-        document.getElementById("r1").setAttribute("fill", "red");
-    }
-  </script>
-</svg>