Don't require getPropertyCSSValue in svg number animation tests

LayoutTests/svg/animations/script-tests/svgnumber-animation-1.js

 description("Test for SVGNumber animation.");
 createSVGTestCase();
 
 // Setup test document
 var rect = createSVGElement("rect");
 rect.setAttribute("id", "rect");
 rect.setAttribute("x", "0");
 rect.setAttribute("width", "100");
 rect.setAttribute("height", "100");
 rect.setAttribute("fill", "green");
 rect.setAttribute("opacity", "0");
 rect.setAttribute("onclick", "executeTest()");
 
 var animate = createSVGElement("animate");
 animate.setAttribute("id", "animation");
 animate.setAttribute("attributeName", "opacity");
 animate.setAttribute("begin", "click");
 animate.setAttribute("dur", "4s");
 animate.setAttribute("from", "0");
 animate.setAttribute("to", "1");
 rect.appendChild(animate);
 rootSVGElement.appendChild(rect);
 
 // Setup animation test
 function sample1() {
     // Check initial/end conditions
-    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)", "0.5");
+    shouldBeCloseEnough("parseFloat(getComputedStyle(rect).opacity)", "0.5");
 }
 
 function sample3() {
-    shouldBeCloseEnough("getComputedStyle(rect).getPropertyCSSValue('opacity').getFloatValue(CSSPrimitiveValue.CSS_NUMBER)", "1");
+    shouldBeCloseEnough("parseFloat(getComputedStyle(rect).opacity)", "1");
 }
 
 function executeTest() {
     const expectedValues = [
         // [animationId, time, sampleCallback]
         ["animation", 0.0,   sample1],
         ["animation", 2.0,   sample2],
         ["animation", 3.999, sample3],
         ["animation", 4.001, sample1]
     ];
 
     runAnimationTest(expectedValues);
 }
 
 var successfullyParsed = true;