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

third_party/WebKit/LayoutTests/platform/linux/paint/invalidation/flexbox/repaint-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow DIV id='content'",
           "rect": [138, 128, 654, 100],
           "reason": "style change"
         },
         {
-          "object": "LayoutBlockFlow P",
-          "rect": [138, 128, 654, 100],
-          "reason": "forced by layout"
-        },
-        {
           "object": "LayoutText #text",
           "rect": [137, 128, 652, 99],
           "reason": "forced by layout"
         },
         {
           "object": "LayoutBlockFlow DIV id='content'",
           "rect": [148, 128, 644, 100],
           "reason": "style change"
         },
         {
-          "object": "LayoutBlockFlow P",
-          "rect": [148, 128, 644, 100],
-          "reason": "forced by layout"
-        },
-        {
           "object": "LayoutText #text",
           "rect": [147, 128, 641, 99],
           "reason": "forced by layout"
         },
         {
           "object": "LayoutBlockFlow DIV id='content'",
           "rect": [400, 128, 392, 160],
           "reason": "style change"
         },
         {
@@ skipping 101 matching lines @@
       "object": "InlineTextBox 'vel varius vestibulum, purus quam mollis sapien, in condimentum leo neque sed nulla. Nunc quis porta elit.'",
       "reason": "forced by layout"
     },
     {
       "object": "InlineTextBox 'Pellentesque erat lectus, ultricies a lobortis id, faucibus id quam.'",
       "reason": "forced by layout"
     }
   ]
 }