Avoid requiring a recalc to update compositing state for iframes

LayoutTests/platform/mac/editing/selection/4975120-expected.txt

Index: LayoutTests/platform/mac/editing/selection/4975120-expected.txt
diff --git a/LayoutTests/platform/mac/editing/selection/4975120-expected.txt b/LayoutTests/platform/mac/editing/selection/4975120-expected.txt
index 3f991ebc02c461cf2fac095f8a008be03b39dbbf..70d1b82ebaf4143a59549113f4179aae8cd6ce4b 100644
--- a/LayoutTests/platform/mac/editing/selection/4975120-expected.txt
+++ b/LayoutTests/platform/mac/editing/selection/4975120-expected.txt
@@ -10,17 +10,18 @@ layer at (0,0) size 800x600
       RenderBlock (anonymous) at (0,52) size 784x177
         RenderTextControl {INPUT} at (2,2) size 123x19 [bgcolor=#FFFFFF] [border: (2px inset #EEEEEE)]
         RenderBR {BR} at (127,16) size 0x0
-        RenderPartObject {IFRAME} at (0,23) size 304x154 [border: (2px inset #EEEEEE)]
-          layer at (0,0) size 300x150
-            RenderView at (0,0) size 300x150
-          layer at (0,0) size 300x150
-            RenderBlock {HTML} at (0,0) size 300x150
-              RenderBody {BODY} at (8,8) size 284x134 [bgcolor=#FFFFE0]
         RenderText {#text} at (0,0) size 0x0
         RenderText {#text} at (0,0) size 0x0
 layer at (13,65) size 117x13
   RenderBlock {DIV} at (3,3) size 117x13
     RenderText {#text} at (0,0) size 18x13
       text run at (0,0) width 18: "foo"
+layer at (8,83) size 304x154
+  RenderPartObject {IFRAME} at (0,23) size 304x154 [border: (2px inset #EEEEEE)]
+    layer at (0,0) size 300x150
+      RenderView at (0,0) size 300x150
+    layer at (0,0) size 300x150
+      RenderBlock {HTML} at (0,0) size 300x150
+        RenderBody {BODY} at (8,8) size 284x134 [bgcolor=#FFFFE0]
 selection start: position 0 of child 0 {#text} of child 0 {DIV} of {#document-fragment} of child 3 {INPUT} of body
 selection end:   position 3 of child 0 {#text} of child 0 {DIV} of {#document-fragment} of child 3 {INPUT} of body