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

third_party/WebKit/LayoutTests/platform/linux/paint/invalidation/gradients-em-stops-repaint-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow DIV class='em-units'",
           "rect": [8, 8, 784, 147],
           "reason": "forced by layout"
-        },
-        {
-          "object": "LayoutBlockFlow DIV id='box4' class='box'",
-          "rect": [344, 18, 302, 122],
-          "reason": "style change"
-        },
-        {
-          "object": "LayoutBlockFlow DIV id='box3' class='box'",
-          "rect": [18, 18, 302, 122],
-          "reason": "forced by layout"
-        },
-        {
-          "object": "LayoutBlockFlow DIV class='indicator'",
-          "rect": [345, 19, 240, 20],
-          "reason": "style change"
-        },
-        {
-          "object": "LayoutText #text",
-          "rect": [330, 135, 4, 19],
-          "reason": "forced by layout"
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
       "object": "LayoutBlockFlow DIV class='em-units'",
       "reason": "forced by layout"
     },
     {
@@ skipping 16 matching lines @@
       "object": "LayoutBlockFlow DIV id='box4' class='box'",
       "reason": "style change"
     },
     {
       "object": "LayoutBlockFlow DIV class='indicator'",
       "reason": "style change"
     }
   ]
 }