Fix gradient background invalidation when HTML size changes

third_party/WebKit/LayoutTests/platform/linux/paint/invalidation/table-shrink-row-repaint-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [785, 850],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
-          "object": "LayoutBlockFlow HTML",
-          "rect": [0, 0, 785, 1050],
-          "reason": "forced by layout"
-        },
-        {
           "object": "LayoutView #document",
           "rect": [0, 850, 785, 200],
           "reason": "incremental"
         },
         {
           "object": "LayoutTableCell TD id='resizeMe'",
           "rect": [8, 117, 769, 205],
           "reason": "incremental"
         },
         {
@@ skipping 238 matching lines @@
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
       "object": "LayoutView #document",
       "reason": "incremental"
     },
     {
-      "object": "LayoutBlockFlow HTML",
-      "reason": "forced by layout"
-    },
-    {
       "object": "LayoutTableCell TD id='resizeMe'",
       "reason": "incremental"
     },
     {
       "object": "LayoutTableCell TD",
       "reason": "bounds change"
     },
     {
       "object": "RootInlineBox",
       "reason": "bounds change"
@@ skipping 178 matching lines @@
       "object": "LayoutText #text",
       "reason": "bounds change"
     },
     {
       "object": "InlineTextBox '13'",
       "reason": "bounds change"
     }
   ]
 }