Drop redundant null checks in SVGListPropertyTearOffHelper

LayoutTests/svg/dom/SVGPointList-basics.xhtml

Index: LayoutTests/svg/dom/SVGPointList-basics.xhtml
diff --git a/LayoutTests/svg/dom/SVGPointList-basics.xhtml b/LayoutTests/svg/dom/SVGPointList-basics.xhtml
index 3f6a757d2eae6957b4df1cbf86987866c195b4e1..092c40c105a77bf36b50ccc6da5e4210906f4205 100644
--- a/LayoutTests/svg/dom/SVGPointList-basics.xhtml
+++ b/LayoutTests/svg/dom/SVGPointList-basics.xhtml
@@ -123,6 +123,13 @@
     shouldThrow("poly1.points.replaceItem(1, 0)");
 
     debug("");
+    debug("Test uncommon values for indexed setter");
+    shouldThrow("poly1.points[0] = 30");
+    shouldThrow("poly1.points[0] = 'aString'");
+    shouldThrow("poly1.points[0] = poly1");
+    shouldThrow("poly1.points[0] = null");
+
+    debug("");
     debug("Test uncommon arguments for replaceItem() and xml-dom synchronization");
     shouldBe("poly1.points.numberOfItems", "4");
     shouldBeEqualToString("dumpPoint(poly1.points.getItem(0))", "x=0 y=0");