[SVG] Position set by low priority animation is ignored even though it is active

LayoutTests/svg/animations/script-tests/animateMotion-multiple.js

+description("Test for checking position of the svg element when multiple animateMotion are acting on it");
+embedSVGTestCase("resources/animateMotion-multiple.svg");
+
+// Setup animation test
+function sample1() {
+    shouldBeCloseEnough("rootSVGElement.getBBox().x", "20");
+}
+
+function sample2() {
+    shouldBeCloseEnough("rootSVGElement.getBBox().x", "20");
+}
+
+function sample3() {
+    shouldBeCloseEnough("rootSVGElement.getBBox().x", "40");
+}
+
+function sample4() {
+    shouldBeCloseEnough("rootSVGElement.getBBox().x", "60");
+}
+
+function sample5() {
+    shouldBeCloseEnough("rootSVGElement.getBBox().x", "20");
+}
+
+function sample6() {
+    shouldBeCloseEnough("rootSVGElement.getBBox().x", "20");
+}
+
+function executeTest() {
+    var rects = rootSVGElement.ownerDocument.getElementsByTagName("rect");
+    rect1 = rects[0];
+
+    const expectedValues = [
+        // [animationId, time, sampleCallback]
+        ["anim", 0.0,   sample1],
+        ["anim", 1.0,   sample2],
+        ["anim", 2.0,   sample3],
+        ["anim", 4.0,   sample4],
+        ["anim", 6.0,   sample5],
+        ["anim", 7.0,   sample6]
+    ];
+
+    runAnimationTest(expectedValues);
+}
+
+window.animationStartsImmediately = true;
+var successfullyParsed = true;