Avoid requiring a recalc to update compositing state for iframes

LayoutTests/platform/mac/fast/flexbox/016-expected.txt

Index: LayoutTests/platform/mac/fast/flexbox/016-expected.txt
diff --git a/LayoutTests/fast/flexbox/016-expected.txt b/LayoutTests/platform/mac/fast/flexbox/016-expected.txt
similarity index 78%
copy from LayoutTests/fast/flexbox/016-expected.txt
copy to LayoutTests/platform/mac/fast/flexbox/016-expected.txt
index 36419132dc0fc280806b96a46612ef1dbe7b5636..7bc316971a27b7b94d7b17dc5f4de2d2c0d6b531 100644
--- a/LayoutTests/fast/flexbox/016-expected.txt
+++ b/LayoutTests/platform/mac/fast/flexbox/016-expected.txt
@@ -12,13 +12,14 @@ layer at (0,0) size 800x585
             text run at (0,18) width 254: "filled with an olive-bordered green box. "
             text run at (254,18) width 499: "It should start beneath the header, end above the footer, and fill the width of the"
             text run at (0,36) width 111: "browser window."
-        RenderPartObject {IFRAME} at (0,54) size 812x513 [bgcolor=#008000] [border: (10px solid #808000)]
-          layer at (0,0) size 792x493
-            RenderView at (0,0) size 792x493
-          layer at (0,0) size 792x493
-            RenderBlock {HTML} at (0,0) size 792x493
-              RenderBody {BODY} at (8,8) size 776x477
         RenderBlock {DIV} at (0,567) size 800x18
           RenderText {#text} at (0,0) size 664x18
             text run at (0,0) width 407: "This footer should remain at the bottom of the browser window. "
             text run at (407,0) width 257: "It can wrap to multiple lines if necessary."
+layer at (0,54) size 812x513
+  RenderPartObject {IFRAME} at (0,54) size 812x513 [bgcolor=#008000] [border: (10px solid #808000)]
+    layer at (0,0) size 792x493
+      RenderView at (0,0) size 792x493
+    layer at (0,0) size 792x493
+      RenderBlock {HTML} at (0,0) size 792x493
+        RenderBody {BODY} at (8,8) size 776x477