Eagerly invalidate when a layer becomes stacking context

third_party/WebKit/LayoutTests/platform/linux/paint/invalidation/scroll-descendant-with-cached-cliprects-expected.txt

 {
   "layers": [
     {
       "name": "LayoutView #document",
       "bounds": [785, 1895],
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
         {
           "object": "LayoutBlockFlow (positioned) DIV id='scrollpanel'",
           "rect": [677, 252, 100, 100],
           "reason": "subtree"
         },
         {
-          "object": "LayoutBlockFlow (relative positioned) DIV id='ul'",
-          "rect": [677, 252, 100, 100],
-          "reason": "subtree"
-        },
-        {
-          "object": "LayoutBlockFlow DIV",
-          "rect": [677, 252, 100, 100],
-          "reason": "subtree"
-        },
-        {
-          "object": "LayoutBlockFlow (positioned) DIV id='scrollpanel'",
+          "object": "LayoutBlockFlow (relative positioned) DIV class='container'",
           "rect": [677, 52, 100, 100],
           "reason": "subtree"
         },
         {
           "object": "LayoutBlockFlow (relative positioned) DIV id='ul'",
           "rect": [677, 52, 100, 100],
           "reason": "subtree"
         },
         {
           "object": "LayoutBlockFlow DIV",
           "rect": [677, 52, 100, 100],
           "reason": "subtree"
+        },
+        {
+          "object": "LayoutBlockFlow DIV id='scrollpanel'",
+          "rect": [677, 52, 100, 100],
+          "reason": "subtree"
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
+      "object": "LayoutBlockFlow DIV id='scrollpanel'",
+      "reason": "subtree"
+    },
+    {
+      "object": "LayoutBlockFlow (relative positioned) DIV class='container'",
+      "reason": "subtree"
+    },
+    {
+      "object": "LayoutBlockFlow (relative positioned) DIV id='ul'",
+      "reason": "subtree"
+    },
+    {
+      "object": "LayoutBlockFlow DIV",
+      "reason": "subtree"
+    },
+    {
       "object": "LayoutBlockFlow (positioned) DIV id='scrollpanel'",
       "reason": "style change"
     },
     {
       "object": "LayoutBlockFlow (relative positioned) DIV class='container'",
       "reason": "style change"
     },
     {
       "object": "LayoutBlockFlow (relative positioned) DIV id='ul'",
       "reason": "style change"
@@ skipping 14 matching lines @@
       "object": "LayoutBlockFlow (relative positioned) DIV id='ul'",
       "reason": "subtree"
     },
     {
       "object": "LayoutBlockFlow DIV",
       "reason": "subtree"
     }
   ]
 }