Avoid requiring a recalc to update compositing state for iframes

LayoutTests/platform/win/fast/frames/onlyCommentInIFrame-expected.txt

Index: LayoutTests/platform/win/fast/frames/onlyCommentInIFrame-expected.txt
diff --git a/LayoutTests/platform/win/fast/frames/onlyCommentInIFrame-expected.txt b/LayoutTests/platform/win/fast/frames/onlyCommentInIFrame-expected.txt
index a3f681507af82e8f2127533d4f67d882522ddaff..28994893945d34e1893aed613e4d23ed121d61e4 100644
--- a/LayoutTests/platform/win/fast/frames/onlyCommentInIFrame-expected.txt
+++ b/LayoutTests/platform/win/fast/frames/onlyCommentInIFrame-expected.txt
@@ -8,30 +8,32 @@ layer at (0,0) size 800x600
         text run at (0,20) width 783: "construct RenderViews for such iframes. We need to propery construct an empty frame instead, so the RenderView should have a"
         text run at (0,40) width 435: "RenderBlock and RenderBody below it in the dump of the RenderTree. "
       RenderBR {BR} at (435,55) size 0x0
-      RenderPartObject {IFRAME} at (0,60) size 788x14 [border: (2px inset #EEEEEE)]
-        layer at (0,0) size 784x10
-          RenderView at (0,0) size 784x10
-        layer at (0,0) size 784x10
-          RenderBlock {HTML} at (0,0) size 784x10
-            RenderBody {BODY} at (8,8) size 768x0
       RenderText {#text} at (0,0) size 0x0
       RenderBR {BR} at (0,0) size 0x0
       RenderBR {BR} at (0,74) size 0x19
-      RenderPartObject {IFRAME} at (0,94) size 788x14 [border: (2px inset #EEEEEE)]
-        layer at (0,0) size 769x172
-          RenderView at (0,0) size 769x10
-        layer at (0,0) size 769x172
-          RenderBlock {html} at (0,0) size 769x171.88
-            RenderBody {body} at (8,16) size 753x139.88
-              RenderBlock {parsererror} at (16,0) size 721x139.88 [bgcolor=#FFDDDD] [border: (2px solid #CC7777)]
-                RenderBlock {h3} at (18,20.72) size 685x23
-                  RenderText {#text} at (0,0) size 324x22
-                    text run at (0,0) width 324: "This page contains the following errors:"
-                RenderBlock {div} at (18,62.44) size 685x15
-                  RenderText {#text} at (0,0) size 490x15
-                    text run at (0,0) width 490: "error on line 1 at column 15: Extra content at the end of the document"
-                    text run at (490,0) width 0: " "
-                RenderBlock {h3} at (18,96.16) size 685x23
-                  RenderText {#text} at (0,0) size 430x22
-                    text run at (0,0) width 430: "Below is a rendering of the page up to the first error."
       RenderText {#text} at (0,0) size 0x0
+layer at (8,68) size 788x14
+  RenderPartObject {IFRAME} at (0,60) size 788x14 [border: (2px inset #EEEEEE)]
+    layer at (0,0) size 784x10
+      RenderView at (0,0) size 784x10
+    layer at (0,0) size 784x10
+      RenderBlock {HTML} at (0,0) size 784x10
+        RenderBody {BODY} at (8,8) size 768x0
+layer at (8,102) size 788x14
+  RenderPartObject {IFRAME} at (0,94) size 788x14 [border: (2px inset #EEEEEE)]
+    layer at (0,0) size 769x172
+      RenderView at (0,0) size 769x10
+    layer at (0,0) size 769x172
+      RenderBlock {html} at (0,0) size 769x171.88
+        RenderBody {body} at (8,16) size 753x139.88
+          RenderBlock {parsererror} at (16,0) size 721x139.88 [bgcolor=#FFDDDD] [border: (2px solid #CC7777)]
+            RenderBlock {h3} at (18,20.72) size 685x23
+              RenderText {#text} at (0,0) size 324x22
+                text run at (0,0) width 324: "This page contains the following errors:"
+            RenderBlock {div} at (18,62.44) size 685x15
+              RenderText {#text} at (0,0) size 490x15
+                text run at (0,0) width 490: "error on line 1 at column 15: Extra content at the end of the document"
+                text run at (490,0) width 0: " "
+            RenderBlock {h3} at (18,96.16) size 685x23
+              RenderText {#text} at (0,0) size 430x22
+                text run at (0,0) width 430: "Below is a rendering of the page up to the first error."