Only update composited-scrolling state once after layout.

LayoutTests/virtual/gpu/compositedscrolling/overflow/overflow-scrollbar-layers-expected.txt

Index: LayoutTests/virtual/gpu/compositedscrolling/overflow/overflow-scrollbar-layers-expected.txt
diff --git a/LayoutTests/virtual/gpu/compositedscrolling/overflow/overflow-scrollbar-layers-expected.txt b/LayoutTests/virtual/gpu/compositedscrolling/overflow/overflow-scrollbar-layers-expected.txt
index 8366085fd398279402021acf4ceea713f66dab54..e26c25423e57f39e1087800f65b81885a94c42b1 100644
--- a/LayoutTests/virtual/gpu/compositedscrolling/overflow/overflow-scrollbar-layers-expected.txt
+++ b/LayoutTests/virtual/gpu/compositedscrolling/overflow/overflow-scrollbar-layers-expected.txt
@@ -9,13 +9,17 @@
         (GraphicsLayer
           (position 8.00 13.00)
           (bounds 100.00 100.00)
-          (drawsContent 1)
           (children 2
             (GraphicsLayer
               (bounds 85.00 100.00)
               (children 1
                 (GraphicsLayer
-                  (bounds 10.00 200.00)
+                  (bounds 85.00 200.00)
+                  (children 1
+                    (GraphicsLayer
+                      (bounds 10.00 200.00)
+                    )
+                  )
                 )
               )
             )
@@ -29,13 +33,17 @@
         (GraphicsLayer
           (position 8.00 13.00)
           (bounds 100.00 100.00)
-          (drawsContent 1)
           (children 2
             (GraphicsLayer
               (bounds 100.00 85.00)
               (children 1
                 (GraphicsLayer
-                  (bounds 200.00 10.00)
+                  (bounds 200.00 85.00)
+                  (children 1
+                    (GraphicsLayer
+                      (bounds 200.00 10.00)
+                    )
+                  )
                 )
               )
             )
@@ -49,13 +57,17 @@
         (GraphicsLayer
           (position 8.00 13.00)
           (bounds 100.00 100.00)
-          (drawsContent 1)
           (children 4
             (GraphicsLayer
               (bounds 85.00 85.00)
               (children 1
                 (GraphicsLayer
                   (bounds 200.00 200.00)
+                  (children 1
+                    (GraphicsLayer
+                      (bounds 200.00 200.00)
+                    )
+                  )
                 )
               )
             )