[SVG] SVGAnimatedRect migration to new SVG property impl.

LayoutTests/svg/custom/script-tests/immutable-properties.js

 description("Tests whether immutable properties can not be modified.");
 
 var svgDoc = document.implementation.createDocument("http://www.w3.org/2000/svg", "svg", null);
 
 // 'viewport' attribute is immutable (Spec: The object itself and its contents are both readonly.)
 var viewport = svgDoc.documentElement.viewport;
 
 shouldBe("viewport.x", "0");
 viewport.x = 100;
 
 shouldBe("viewport.x", "100");
 shouldBe("svgDoc.documentElement.viewport.x", "0");
 
 // Every attribute of SVGZoomEvent is immutable (Spec: The object itself and its contents are both readonly.)
 var zoomEvent = svgDoc.createEvent("SVGZoomEvents");
 
 // 'zoomRectScreen' property
 var zoomRectScreen = zoomEvent.zoomRectScreen;
 
 shouldBe("zoomRectScreen.x", "0");
-zoomRectScreen.x = 100;
-
-shouldBe("zoomRectScreen.x", "100");
-shouldBe("zoomEvent.zoomRectScreen.x", "0");
+shouldThrow("zoomRectScreen.x = 100;");
 
 // 'previousScale' property
 shouldBe("zoomEvent.previousScale", "0")
 zoomEvent.previousScale = 200;
 shouldBe("zoomEvent.previousScale", "0")
 
 // 'previousTranslate' property
 var previousTranslate = zoomEvent.previousTranslate;
 
 shouldBe("previousTranslate.x", "0");
@@ skipping 10 matching lines @@
 // 'newTranslate' property
 var newTranslate = zoomEvent.previousTranslate;
 
 shouldBe("newTranslate.x", "0");
 newTranslate.x = 300;
 
 shouldBe("newTranslate.x", "300");
 shouldBe("zoomEvent.newTranslate.x", "0");
 
 var successfullyParsed = true;