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

third_party/WebKit/LayoutTests/platform/mac-mac10.9/paint/invalidation/textarea-caret-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutTextControl TEXTAREA id='editor'",
           "rect": [5, 5, 167, 38],
           "reason": "subtree"
         },
         {
-          "object": "LayoutBlockFlow DIV id='inner-editor'",
-          "rect": [11, 11, 155, 13],
-          "reason": "subtree"
-        },
-        {
           "object": "LayoutTextControl TEXTAREA id='editor'",
           "rect": [9, 24, 144, 15],
           "reason": "scroll"
         },
         {
           "object": "LayoutText #text",
           "rect": [9, 11, 144, 13],
           "reason": "subtree"
         },
         {
@@ skipping 46 matching lines @@
       "object": "LayoutText #text",
       "reason": "subtree"
     },
     {
       "object": "InlineTextBox '------------------------------------------------------------'",
       "reason": "subtree"
     }
   ]
 }