Don't invalidate rect if it's covered by fully invalidated parent's visual rect

third_party/WebKit/LayoutTests/platform/win/paint/invalidation/compositing/iframe-inside-squashed-layer-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [785, 1016],
       "contentsOpaque": true,
       "drawsContent": true
     },
     {
       "name": "Squashing Containment Layer",
@@ skipping 22 matching lines @@
           "object": "LayoutBlockFlow BODY",
           "rect": [8, 508, 284, 18],
           "reason": "forced by layout"
         },
         {
           "object": "LayoutBlockFlow BODY",
           "rect": [8, 508, 269, 142],
           "reason": "forced by layout"
         },
         {
-          "object": "LayoutText #text",
-          "rect": [8, 508, 31, 17],
-          "reason": "forced by layout"
-        },
-        {
           "object": "LayoutView #document",
           "rect": [285, 500, 15, 150],
           "reason": "scroll"
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
       "object": "LayoutView #document",
@@ skipping 19 matching lines @@
       "object": "LayoutText #text",
       "reason": "forced by layout"
     },
     {
       "object": "InlineTextBox 'test1'",
       "reason": "forced by layout"
     }
   ]
 }