Eagerly invalidate when a layer becomes stacking context

third_party/WebKit/LayoutTests/paint/invalidation/mix-blend-mode-separate-stacking-context-expected.txt

Index: third_party/WebKit/LayoutTests/paint/invalidation/mix-blend-mode-separate-stacking-context-expected.txt
diff --git a/third_party/WebKit/LayoutTests/paint/invalidation/mix-blend-mode-separate-stacking-context-expected.txt b/third_party/WebKit/LayoutTests/paint/invalidation/mix-blend-mode-separate-stacking-context-expected.txt
index a3636bbdcbb09b4c339ea584276aca66598c58db..1c9d14be01a47c321e5fb22d524aee652c1dd165 100644
--- a/third_party/WebKit/LayoutTests/paint/invalidation/mix-blend-mode-separate-stacking-context-expected.txt
+++ b/third_party/WebKit/LayoutTests/paint/invalidation/mix-blend-mode-separate-stacking-context-expected.txt
@@ -12,6 +12,16 @@
           "reason": "subtree"
         },
         {
+          "object": "LayoutBlockFlow (floating) DIV",
+          "rect": [348, 48, 60, 60],
+          "reason": "subtree"
+        },
+        {
+          "object": "LayoutBlockFlow (floating) DIV id='fourth'",
+          "rect": [328, 28, 60, 60],
+          "reason": "subtree"
+        },
+        {
           "object": "LayoutBlockFlow (relative positioned) (floating) DIV id='fourth'",
           "rect": [328, 28, 60, 60],
           "reason": "subtree"
@@ -35,12 +45,25 @@
           "object": "LayoutBlockFlow (floating) DIV id='first'",
           "rect": [48, 48, 60, 60],
           "reason": "subtree"
+        },
+        {
+          "object": "LayoutBlockFlow (floating) DIV id='first'",
+          "rect": [48, 48, 60, 60],
+          "reason": "subtree"
         }
       ]
     }
   ],
   "objectPaintInvalidations": [
     {
+      "object": "LayoutBlockFlow (floating) DIV id='fourth'",
+      "reason": "subtree"
+    },
+    {
+      "object": "LayoutBlockFlow (floating) DIV",
+      "reason": "subtree"
+    },
+    {
       "object": "LayoutBlockFlow (floating) DIV id='second'",
       "reason": "subtree"
     },
@@ -49,6 +72,10 @@
       "reason": "subtree"
     },
     {
+      "object": "LayoutBlockFlow (floating) DIV id='first'",
+      "reason": "subtree"
+    },
+    {
       "object": "LayoutBlockFlow (floating) DIV id='second'",
       "reason": "subtree"
     },