add 'slow' prefix to RenderObject's firstChild() / lastChild() methods

Source/core/rendering/svg/SVGResourcesCycleSolver.cpp

Index: Source/core/rendering/svg/SVGResourcesCycleSolver.cpp
diff --git a/Source/core/rendering/svg/SVGResourcesCycleSolver.cpp b/Source/core/rendering/svg/SVGResourcesCycleSolver.cpp
index efa1b933394642db2fa8371f6307be2b458e26f2..f1a40d490b9bdebf0d91c30a7f1fd5039e7e21d9 100644
--- a/Source/core/rendering/svg/SVGResourcesCycleSolver.cpp
+++ b/Source/core/rendering/svg/SVGResourcesCycleSolver.cpp
@@ -69,7 +69,7 @@ bool SVGResourcesCycleSolver::resourceContainsCycles(RenderObject* renderer) con
     // Then operate on the child resources of the given renderer.
     // <marker id="a"> <path marker-start="url(#b)"/> ...
     // <marker id="b"> <path marker-start="url(#a)"/> ...
-    for (RenderObject* child = renderer->firstChild(); child; child = child->nextSibling()) {
+    for (RenderObject* child = renderer->slowFirstChild(); child; child = child->nextSibling()) {
         SVGResources* childResources = SVGResourcesCache::cachedResourcesForRenderObject(child);
         if (!childResources)
             continue;