Don't require getPropertyCSSValue in svg tests

LayoutTests/svg/animations/script-tests/change-css-property-while-animating-fill-freeze.js

 description("This tests scripting a CSS property while animation is running");
 embedSVGTestCase("resources/change-css-property-while-animating-fill-freeze.svg");
 
 // Setup animation test
 function sample1() {
-    shouldBeCloseEnough("getComputedStyle(rect).getPropertyCSSValue('opacity').getFloatValue(CSSPrimitiveValue.CSS_NUMBER)", "0");
+    shouldBeCloseEnough("parseFloat(getComputedStyle(rect).opacity)", "0");
 }
 
 function sample2() {
-    shouldBeCloseEnough("getComputedStyle(rect).getPropertyCSSValue('opacity').getFloatValue(CSSPrimitiveValue.CSS_NUMBER)", "0.25");
+    shouldBeCloseEnough("parseFloat(getComputedStyle(rect).opacity)", "0.25");
     rect.setAttribute("opacity", "1");
 }
 
 function sample3() {
-    shouldBeCloseEnough("getComputedStyle(rect).getPropertyCSSValue('opacity').getFloatValue(CSSPrimitiveValue.CSS_NUMBER)", "0.25");
+    shouldBeCloseEnough("parseFloat(getComputedStyle(rect).opacity)", "0.25");
 }
 
 function sample4() {
-    shouldBeCloseEnough("getComputedStyle(rect).getPropertyCSSValue('opacity').getFloatValue(CSSPrimitiveValue.CSS_NUMBER)", "0.5");
+    shouldBeCloseEnough("parseFloat(getComputedStyle(rect).opacity)", "0.5");
 }
 
 function sample5() {
-    shouldBeCloseEnough("getComputedStyle(rect).getPropertyCSSValue('opacity').getFloatValue(CSSPrimitiveValue.CSS_NUMBER)", "0.5");
+    shouldBeCloseEnough("parseFloat(getComputedStyle(rect).opacity)", "0.5");
 }
 
 function executeTest() {
     rect = rootSVGElement.ownerDocument.getElementsByTagName("rect")[0];
 
     const expectedValues = [
         // [animationId, time, sampleCallback]
         ["an1", 0.0,   sample1],
         ["an1", 2.0,   sample2],
         ["an1", 2.001, sample3],
         ["an1", 3.999, sample4],
         ["an1", 4.001, sample5],
         ["an1", 60.0,  sample5]
     ];
 
     runAnimationTest(expectedValues);
 }
 
 window.animationStartsImmediately = true;
 var successfullyParsed = true;