Use Traversal<>::firstChild() instead of firstWithin() when iterating over children

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 5dcc52aab6ac6b592edc574f42c8086209d33c65..ead76067d295cd073d3d9f8d673fdbc1b3108af4 100644
--- a/Source/core/rendering/svg/RenderSVGResourceMasker.cpp
+++ b/Source/core/rendering/svg/RenderSVGResourceMasker.cpp
@@ -137,7 +137,7 @@ 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::firstWithin(*element()); childElement; childElement = ElementTraversal::nextSibling(*childElement)) {
+    for (Element* childElement = ElementTraversal::firstChild(*element()); childElement; childElement = ElementTraversal::nextSibling(*childElement)) {
         RenderObject* renderer = childElement->renderer();
         if (!childElement->isSVGElement() || !renderer)
             continue;