Put SVGResourceContainer subtypes into their own property trees.

third_party/WebKit/LayoutTests/paint/invalidation/svg/window-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutSVGContainer g id='Windows'",
@@ skipping 232 matching lines @@
         },
         {
           "object": "LayoutSVGPath line",
           "rect": [350, 192, 10, 3],
           "reason": "layoutObject insertion"
         },
         {
           "object": "LayoutSVGPath line",
           "rect": [428, 388, 10, 2],
           "reason": "layoutObject insertion"
-        },
-        {
-          "object": "LayoutSVGPath line",
-          "rect": [-1, 21, 7, 11],
-          "reason": "layoutObject insertion"
-        },
-        {
-          "object": "LayoutSVGPath line",
-          "rect": [-1, 21, 7, 11],
-          "reason": "layoutObject insertion"
-        },
-        {
-          "object": "LayoutSVGRect rect",
-          "rect": [-1, 21, 7, 11],
-          "reason": "layoutObject insertion"
-        },
-        {
-          "object": "LayoutSVGPath line",
-          "rect": [-1, 29, 6, 3],
-          "reason": "layoutObject insertion"
-        },
-        {
-          "object": "LayoutSVGRect rect",
-          "rect": [0, 22, 5, 9],
-          "reason": "layoutObject insertion"
-        },
-        {
-          "object": "LayoutSVGRect rect",
-          "rect": [0, 22, 5, 9],
-          "reason": "layoutObject insertion"
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
       "object": "LayoutSVGHiddenContainer symbol id='closeButton'",
       "reason": "layoutObject insertion"
     },
     {
@@ skipping 1012 matching lines @@
       "object": "LayoutSVGRect rect",
       "reason": "bounds change"
     },
     {
       "object": "LayoutSVGPath line",
       "reason": "bounds change"
     }
   ]
 }