Remove support for <animateColor>.

LayoutTests/svg/custom/animation-currentColor.svg

Index: LayoutTests/svg/custom/animation-currentColor.svg
diff --git a/LayoutTests/svg/custom/animation-currentColor.svg b/LayoutTests/svg/custom/animation-currentColor.svg
index deea34f3674c52fbe5844654f61bfb0cfea978c5..9197d5b29f2d55eeb61749562c86a50943a45ffc 100644
--- a/LayoutTests/svg/custom/animation-currentColor.svg
+++ b/LayoutTests/svg/custom/animation-currentColor.svg
@@ -1,15 +1,15 @@
 <svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
 <rect x="10" y="10" width="50" height="50" color="green" fill="red">
-    <animateColor attributeName="fill" from="green" to="currentColor" begin="0s" dur="1s" fill="freeze"/>
+    <animate attributeName="fill" from="green" to="currentColor" begin="0s" dur="1s" fill="freeze"/>
 </rect>
 <rect x="60" y="10" width="50" height="50" color="green" fill="red">
-    <animateColor attributeName="fill" from="currentColor" to="currentColor" begin="0s" dur="1s" fill="freeze"/>
+    <animate attributeName="fill" from="currentColor" to="currentColor" begin="0s" dur="1s" fill="freeze"/>
 </rect>
 <rect x="10" y="60" width="50" height="50" color="green" fill="red">
-    <animateColor attributeName="fill" from="currentColor" by="black" begin="0s" dur="1s" fill="freeze"/>
+    <animate attributeName="fill" from="currentColor" by="black" begin="0s" dur="1s" fill="freeze"/>
 </rect>
 <rect x="60" y="60" width="50" height="50" color="black" fill="red">
-    <animateColor attributeName="fill" from="green" by="currentColor" begin="0s" dur="1s" fill="freeze"/>
+    <animate attributeName="fill" from="green" by="currentColor" begin="0s" dur="1s" fill="freeze"/>
 </rect>
 <rect x="10" y="110" width="50" height="50" color="green" fill="red">
     <animate attributeName="fill" from="green" to="currentColor" begin="0s" dur="1s" accumulate="sum" fill="freeze" />