Put SVGResourceContainer subtypes into their own property trees.

third_party/WebKit/LayoutTests/paint/invalidation/svg/repaint-paintorder-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutSVGPath polygon",
@@ skipping 25 matching lines @@
           "rect": [47, 166, 133, 132],
           "reason": "style change"
         },
         {
           "object": "LayoutSVGContainer use id='t2'",
           "rect": [184, 166, 132, 132],
           "reason": "style change"
         },
         {
           "object": "LayoutSVGEllipse circle id='t4'",
-          "rect": [46, 28, 7, 7],
+          "rect": [1, 1, 8, 8],
           "reason": "style change"
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
       "object": "LayoutSVGEllipse circle id='t4'",
       "reason": "style change"
     },
@@ skipping 29 matching lines @@
       "object": "LayoutSVGPath polygon id='t3'",
       "reason": "style change"
     },
     {
       "object": "LayoutSVGPath polygon",
       "reason": "style change"
     }
   ]
 }