SVGTests should not leave detached elements in the tree

LayoutTests/svg/dynamic-updates/script-tests/SVGPolylineElement-dom-requiredFeatures.js

Index: LayoutTests/svg/dynamic-updates/script-tests/SVGPolylineElement-dom-requiredFeatures.js
diff --git a/LayoutTests/svg/dynamic-updates/script-tests/SVGPolylineElement-dom-requiredFeatures.js b/LayoutTests/svg/dynamic-updates/script-tests/SVGPolylineElement-dom-requiredFeatures.js
index 416b4e0f289ee076ffc7c95a71459179f4e92070..b0512aa8b47d0fe14d0032bd40fd5c7eff5385bc 100644
--- a/LayoutTests/svg/dynamic-updates/script-tests/SVGPolylineElement-dom-requiredFeatures.js
+++ b/LayoutTests/svg/dynamic-updates/script-tests/SVGPolylineElement-dom-requiredFeatures.js
@@ -10,19 +10,19 @@ rootSVGElement.appendChild(polylineElement);
 
 function repaintTest() {
     debug("Check that SVGPolylineElement is initially displayed");
-    shouldBeEqualToString("document.defaultView.getComputedStyle(polylineElement, null).display", "inline");
+    shouldHaveBBox("polylineElement", "200", "200");
     debug("Check that setting requiredFeatures to something invalid makes it not render");
     polylineElement.setAttribute("requiredFeatures", "http://www.w3.org/TR/SVG11/feature#BogusFeature");
-    shouldBeEqualToString("document.defaultView.getComputedStyle(polylineElement, null).display", "");
+    shouldHaveBBox("polylineElement", "0", "0");
     debug("Check that setting requiredFeatures to something valid makes it render again");
     polylineElement.setAttribute("requiredFeatures", "http://www.w3.org/TR/SVG11/feature#Shape");
-    shouldBeEqualToString("document.defaultView.getComputedStyle(polylineElement, null).display", "inline");
+    shouldHaveBBox("polylineElement", "200", "200");
     debug("Check that adding something valid to requiredFeatures keeps rendering the element");
     polylineElement.setAttribute("requiredFeatures", "http://www.w3.org/TR/SVG11/feature#Gradient");
-    shouldBeEqualToString("document.defaultView.getComputedStyle(polylineElement, null).display", "inline");
+    shouldHaveBBox("polylineElement", "200", "200");
     debug("Check that adding something invalid to requiredFeatures makes it not render");
     polylineElement.setAttribute("requiredFeatures", "http://www.w3.org/TR/SVG11/feature#BogusFeature");
-    shouldBeEqualToString("document.defaultView.getComputedStyle(polylineElement, null).display", "");
+    shouldHaveBBox("polylineElement", "0", "0");
 
     completeTest();
 }