Scaling and offset fix for FELighting (software and skia paths)

LayoutTests/svg/dynamic-updates/script-tests/SVGFESpotLightElement-dom-pointsAtY-attr.js

 // [Name] SVGFESpotLightElement-dom-pointsAtY-attr.js
 // [Expected rendering result] A shining cone (performed by diffuse lighting) - and a series of PASS messages
 
 description("Tests dynamic updates of the 'pointsAtY' attribute of the SVGFESpotLightElement object")
 createSVGTestCase();
 
 var spotLightElement = createSVGElement("feSpotLight");
-spotLightElement.setAttribute("x", "113");
-spotLightElement.setAttribute("y", "0");
+spotLightElement.setAttribute("x", "83");
+spotLightElement.setAttribute("y", "-30");
 spotLightElement.setAttribute("z", "100");
-spotLightElement.setAttribute("pointsAtX", "113");
-spotLightElement.setAttribute("pointsAtY", "0");
+spotLightElement.setAttribute("pointsAtX", "83");
+spotLightElement.setAttribute("pointsAtY", "-30");
 spotLightElement.setAttribute("pointsAtZ", "0");
 spotLightElement.setAttribute("specularExponent", "1");
 spotLightElement.setAttribute("limitingConeAngle", "15");
 
 var gradientElement = createSVGElement("feDiffuseLighting");
 gradientElement.setAttribute("surfaceScale", "1");
 gradientElement.setAttribute("diffuseConstant", "1");
 gradientElement.setAttribute("lighting-color", "aqua");
 gradientElement.appendChild(spotLightElement);
 
 var filterElement = createSVGElement("filter");
 filterElement.setAttribute("id", "myFilter");
 filterElement.setAttribute("filterUnits", "userSpaceOnUse");
 filterElement.setAttribute("width", "200");
 filterElement.setAttribute("height", "200");
 filterElement.appendChild(gradientElement);
 
 var defsElement = createSVGElement("defs");
 defsElement.appendChild(filterElement);
 
 rootSVGElement.appendChild(defsElement);
 
 var rectElement = createSVGElement("rect");
 rectElement.setAttribute("width", "200");
 rectElement.setAttribute("height", "200");
 rectElement.setAttribute("filter", "url(#myFilter)");
 rootSVGElement.appendChild(rectElement);
 
-shouldBeEqualToString("spotLightElement.getAttribute('pointsAtY')", "0");
+shouldBeEqualToString("spotLightElement.getAttribute('pointsAtY')", "-30");
 
 function repaintTest() {
-    spotLightElement.setAttribute("pointsAtY", "100");
-    shouldBeEqualToString("spotLightElement.getAttribute('pointsAtY')", "100");
+    spotLightElement.setAttribute("pointsAtY", "70");
+    shouldBeEqualToString("spotLightElement.getAttribute('pointsAtY')", "70");
 
     completeTest();
 }
 
 
 var successfullyParsed = true;