[SPInvalidation] Handle pixel-snapping of paint invalidation rects

third_party/WebKit/LayoutTests/flag-specific/enable-blink-features=SlimmingPaintInvalidation/paint/invalidation/border-radius-repaint-2-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [874, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "backgroundColor": "#3F3F3F",
       "paintInvalidations": [
         {
           "object": "LayoutView #document",
           "rect": [0, 600, 874, 180],
           "reason": "incremental"
         },
         {
           "object": "LayoutBlockFlow DIV",
           "rect": [8, 8, 866, 764],
-          "reason": "border box change"
+          "reason": "bounds change"
         },
         {
           "object": "LayoutBlockFlow HTML",
           "rect": [0, 0, 800, 780],
           "reason": "forced by layout"
         },
         {
           "object": "LayoutBlockFlow BODY",
           "rect": [8, 224, 784, 548],
           "reason": "incremental"
         },
         {
           "object": "LayoutBlockFlow DIV",
           "rect": [137, 88, 607, 604],
-          "reason": "border box change"
+          "reason": "bounds change"
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
       "object": "LayoutView #document",
       "reason": "incremental"
     },
     {
       "object": "LayoutBlockFlow HTML",
       "reason": "forced by layout"
     },
     {
       "object": "LayoutBlockFlow BODY",
       "reason": "incremental"
     },
     {
       "object": "LayoutBlockFlow DIV",
-      "reason": "border box change"
+      "reason": "bounds change"
     },
     {
       "object": "LayoutBlockFlow DIV",
-      "reason": "border box change"
+      "reason": "bounds change"
     }
   ]
 }