Make all PaintLayers that scroll overflow self-painting.

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

Index: third_party/WebKit/LayoutTests/platform/mac/paint/invalidation/textarea-caret-expected.txt
diff --git a/third_party/WebKit/LayoutTests/platform/mac/paint/invalidation/textarea-caret-expected.txt b/third_party/WebKit/LayoutTests/platform/mac/paint/invalidation/textarea-caret-expected.txt
index 2b5b866b17c6dd9ac7408ed4f0a8e6324b5b52c7..91adee6c4260b7f24978e385791f6a37849d4568 100644
--- a/third_party/WebKit/LayoutTests/platform/mac/paint/invalidation/textarea-caret-expected.txt
+++ b/third_party/WebKit/LayoutTests/platform/mac/paint/invalidation/textarea-caret-expected.txt
@@ -6,6 +6,11 @@
       "contentsOpaque": true,
       "drawsContent": true,
       "paintInvalidations": [
+        {
+          "object": "LayoutBlockFlow BODY",
+          "rect": [8, 8, 784, 36],
+          "reason": "geometry"
+        },
         {
           "object": "LayoutTextControl TEXTAREA id='editor'",
           "rect": [5, 5, 147, 38],
@@ -35,6 +40,14 @@
     }
   ],
   "objectPaintInvalidations": [
+    {
+      "object": "LayoutBlockFlow BODY",
+      "reason": "geometry"
+    },
+    {
+      "object": "RootInlineBox",
+      "reason": "geometry"
+    },
     {
       "object": "LayoutTextControl TEXTAREA id='editor'",
       "reason": "subtree"