Updated SVGListPropertyHelper as per SVG2 Spec

LayoutTests/TestExpectations

Index: LayoutTests/TestExpectations
diff --git a/LayoutTests/TestExpectations b/LayoutTests/TestExpectations
index 22d1c2b974a4a3dc4c764931ccdb84d29a2eccaf..781b396708e7109f45280fc744602b34ec46cd4e 100644
--- a/LayoutTests/TestExpectations
+++ b/LayoutTests/TestExpectations
@@ -702,6 +702,16 @@ crbug.com/271243 http/tests/misc/acid3.html [ Pass Failure ]
 
 crbug.com/278497 [ Mac Win ] http/tests/security/contentSecurityPolicy/1.1/plugintypes-invalid.html [ Failure Pass  ]
 
+crbug.com/497196 svg/dom/SVGLengthList-appendItem.xhtml [ NeedsRebaseline ]
+crbug.com/497196 svg/dom/SVGLengthList-initialize.xhtml [ NeedsRebaseline ]
+crbug.com/497196 svg/dom/SVGLengthList-insertItemBefore.xhtml [ NeedsRebaseline ]
+crbug.com/497196 svg/dom/SVGLengthList-removeItem.xhtml [ NeedsRebaseline ]
+crbug.com/497196 svg/dom/SVGLengthList-replaceItem.xhtml [ NeedsRebaseline ]
+crbug.com/497196 svg/dom/SVGPathSegList-appendItem.xhtml [ NeedsRebaseline ]
+crbug.com/497196 svg/dom/SVGPathSegList-clear-and-initialize.xhtml [ NeedsRebaseline ]
+crbug.com/497196 svg/dom/SVGPathSegList-insertItemBefore.xhtml [ NeedsRebaseline ]
+crbug.com/497196 svg/dom/SVGPathSegList-replaceItem.xhtml [ NeedsRebaseline ]
+
 crbug.com/280342 [ Linux Win ] http/tests/media/progress-events-generated-correctly.html [ Failure Pass ]
 crbug.com/282081 [ Win Release ] http/tests/security/contentSecurityPolicy/report-only-from-header.php [ Pass Timeout ]
 crbug.com/282086 [ XP Release ] virtual/gpu/fast/canvas/webgl/gl-uniform-arrays.html [ Pass Timeout ]