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

Source/core/rendering/RenderInline.cpp

Index: Source/core/rendering/RenderInline.cpp
diff --git a/Source/core/rendering/RenderInline.cpp b/Source/core/rendering/RenderInline.cpp
index a53a2679907dafb142e17b2bab7d2f5a8452aa8f..b92de8789bd01738d8c59bab180c942a3e37c835 100644
--- a/Source/core/rendering/RenderInline.cpp
+++ b/Source/core/rendering/RenderInline.cpp
@@ -280,7 +280,7 @@ RenderBoxModelObject* RenderInline::continuationBefore(RenderObject* beforeChild
     RenderBoxModelObject* last = this;
     while (curr) {
         if (beforeChild && beforeChild->parent() == curr) {
-            if (curr->firstChild() == beforeChild)
+            if (curr->slowFirstChild() == beforeChild)
                 return last;
             return curr;
         }
@@ -290,7 +290,7 @@ RenderBoxModelObject* RenderInline::continuationBefore(RenderObject* beforeChild
         curr = nextContinuation(curr);
     }
 
-    if (!beforeChild && !last->firstChild())
+    if (!beforeChild && !last->slowFirstChild())
         return nextToLast;
     return last;
 }
@@ -812,7 +812,7 @@ PositionWithAffinity RenderInline::positionForPoint(const LayoutPoint& point)
     RenderBoxModelObject* c = continuation();
     while (c) {
         RenderBox* contBlock = c->isInline() ? c->containingBlock() : toRenderBlock(c);
-        if (c->isInline() || c->firstChild())
+        if (c->isInline() || c->slowFirstChild())
             return c->positionForPoint(parentBlockPoint - contBlock->locationOffset());
         c = toRenderBlock(c)->inlineElementContinuation();
     }