Use new Traversal<> API more in the code base

Source/core/rendering/svg/RenderSVGResourceMasker.cpp

Index: Source/core/rendering/svg/RenderSVGResourceMasker.cpp
diff --git a/Source/core/rendering/svg/RenderSVGResourceMasker.cpp b/Source/core/rendering/svg/RenderSVGResourceMasker.cpp
index ead76067d295cd073d3d9f8d673fdbc1b3108af4..af5fbb04976b8f8904b962fa5b949d51b98c35be 100644
--- a/Source/core/rendering/svg/RenderSVGResourceMasker.cpp
+++ b/Source/core/rendering/svg/RenderSVGResourceMasker.cpp
@@ -137,9 +137,9 @@ PassRefPtr<DisplayList> RenderSVGResourceMasker::asDisplayList(GraphicsContext*
     // with local clips/mask, which may yield incorrect results when mixing objectBoundingBox and
     // userSpaceOnUse units (http://crbug.com/294900).
     context->beginRecording(strokeBoundingBox());
-    for (Element* childElement = ElementTraversal::firstChild(*element()); childElement; childElement = ElementTraversal::nextSibling(*childElement)) {
+    for (SVGElement* childElement = Traversal<SVGElement>::firstChild(*element()); childElement; childElement = Traversal<SVGElement>::nextSibling(*childElement)) {
         RenderObject* renderer = childElement->renderer();
-        if (!childElement->isSVGElement() || !renderer)
+        if (!renderer)
             continue;
         RenderStyle* style = renderer->style();
         if (!style || style->display() == NONE || style->visibility() != VISIBLE)