Avoid requiring a recalc to update compositing state for iframes

LayoutTests/compositing/iframes/iframe-in-composited-layer-expected.txt

Index: LayoutTests/compositing/iframes/iframe-in-composited-layer-expected.txt
diff --git a/LayoutTests/compositing/iframes/iframe-in-composited-layer-expected.txt b/LayoutTests/compositing/iframes/iframe-in-composited-layer-expected.txt
index 1993bc4ae274c20ac0393099b171e94db285cd61..8dfe2be7516060757a6db0bc436bba8fcec2a2f5 100644
--- a/LayoutTests/compositing/iframes/iframe-in-composited-layer-expected.txt
+++ b/LayoutTests/compositing/iframes/iframe-in-composited-layer-expected.txt
@@ -5,14 +5,15 @@ layer at (0,0) size 800x600
     RenderBody {BODY} at (8,8) size 784x584
 layer at (8,8) size 400x400
   RenderBlock {DIV} at (0,0) size 400x400 [bgcolor=#FFFFE0]
-    RenderPartObject {IFRAME} at (7,7) size 386x386 [border: (3px solid #000000)]
-      layer at (0,0) size 900x900
-        RenderView at (0,0) size 365x365
-      layer at (0,0) size 900x900
-        RenderBlock (relative positioned) {HTML} at (0,0) size 900x900
-          RenderBody {BODY} at (8,8) size 884x349
-      layer at (0,0) size 100x100
-        RenderBlock (positioned) {DIV} at (0,0) size 100x100 [bgcolor=#FF0000]
-      layer at (800,800) size 100x100
-        RenderBlock (positioned) {DIV} at (800,800) size 100x100 [bgcolor=#008000]
     RenderText {#text} at (0,0) size 0x0
+layer at (15,15) size 386x386
+  RenderPartObject {IFRAME} at (7,7) size 386x386 [border: (3px solid #000000)]
+    layer at (0,0) size 900x900
+      RenderView at (0,0) size 365x365
+    layer at (0,0) size 900x900
+      RenderBlock (relative positioned) {HTML} at (0,0) size 900x900
+        RenderBody {BODY} at (8,8) size 884x349
+    layer at (0,0) size 100x100
+      RenderBlock (positioned) {DIV} at (0,0) size 100x100 [bgcolor=#FF0000]
+    layer at (800,800) size 100x100
+      RenderBlock (positioned) {DIV} at (800,800) size 100x100 [bgcolor=#008000]