Put SVGResourceContainer subtypes into their own property trees.

third_party/WebKit/LayoutTests/paint/invalidation/svg/js-update-pattern-child-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutSVGRect rect",
           "rect": [10, 100, 430, 80],
           "reason": "SVG resource change"
         },
         {
           "object": "LayoutSVGRect rect",
           "rect": [10, 10, 430, 80],
           "reason": "SVG resource change"
-        },
-        {
-          "object": "LayoutSVGRect rect id='rect'",
-          "rect": [10, 10, 10, 10],
-          "reason": "full"
-        },
-        {
-          "object": "LayoutSVGRect rect id='rect'",
-          "rect": [0, 10, 10, 10],
-          "reason": "full"
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
       "object": "LayoutSVGRect rect id='rect'",
       "reason": "full"
     },
     {
       "object": "LayoutSVGRect rect",
       "reason": "SVG resource change"
     },
     {
       "object": "LayoutSVGRect rect",
       "reason": "SVG resource change"
     }
   ]
 }