Avoid requiring a recalc to update compositing state for iframes

LayoutTests/platform/win/media/media-document-audio-repaint-expected.txt

Index: LayoutTests/platform/win/media/media-document-audio-repaint-expected.txt
diff --git a/LayoutTests/platform/win/media/media-document-audio-repaint-expected.txt b/LayoutTests/platform/win/media/media-document-audio-repaint-expected.txt
index e3e443644c92a63d8baaf4b933c185bb8c3c652f..96e38eefa90dc24776f6b0b05f79e02e17ff5c19 100644
--- a/LayoutTests/platform/win/media/media-document-audio-repaint-expected.txt
+++ b/LayoutTests/platform/win/media/media-document-audio-repaint-expected.txt
@@ -8,32 +8,33 @@ layer at (0,0) size 800x600
           text run at (0,0) width 620: "This tests that in a standalone media document with audio content, the media element repaints correctly "
           text run at (620,0) width 81: "while playing."
       RenderBlock (anonymous) at (0,36) size 784x334
-        RenderPartObject {IFRAME} at (0,0) size 384x334 [border: (2px inset #EEEEEE)]
-          layer at (0,0) size 380x330
-            RenderView at (0,0) size 380x330
-          layer at (0,0) size 380x330
-            RenderBlock {HTML} at (0,0) size 380x330
-              RenderBody {BODY} at (8,8) size 364x314 [bgcolor=#000000]
-          layer at (40,165) size 300x1
-            RenderVideo {VIDEO} at (40,164.50) size 300x1
-          layer at (40,165) size 300x1
-            RenderFlexibleBox {DIV} at (0,0) size 300x1
-              RenderBlock {DIV} at (0,-34) size 300x35
-          layer at (45,131) size 290x30
-            RenderFlexibleBox {DIV} at (5,0) size 290x30 [bgcolor=#141414CC]
-              RenderButton {INPUT} at (9,0) size 30x30
-              RenderSlider {INPUT} at (48,11) size 98.47x8
-                RenderFlexibleBox {DIV} at (0,0) size 98.47x8 [border: (1px solid #E6E6E659)]
-                  RenderBlock {DIV} at (1,-8) size 110.47x24
-                    RenderBlock {DIV} at (32.22,0) size 32x24
-              RenderFlexibleBox {DIV} at (161.47,0) size 25x30 [color=#FFFFFF]
-                RenderBlock (anonymous) at (0,0) size 25x30
-                  RenderText {#text} at (0,7) size 25x16
-                    text run at (0,7) width 25: "0:00"
-              RenderButton {INPUT} at (195.47,0) size 35x30
-              RenderSlider {INPUT} at (236.47,11) size 38.53x8
-                RenderFlexibleBox {DIV} at (0,0) size 38.53x8 [border: (1px solid #E6E6E659)]
-                  RenderBlock {DIV} at (1,-8) size 50.53x24
-                    RenderBlock {DIV} at (19.53,0) size 24x24
         RenderText {#text} at (0,0) size 0x0
         RenderText {#text} at (0,0) size 0x0
+layer at (8,44) size 384x334
+  RenderPartObject {IFRAME} at (0,0) size 384x334 [border: (2px inset #EEEEEE)]
+    layer at (0,0) size 380x330
+      RenderView at (0,0) size 380x330
+    layer at (0,0) size 380x330
+      RenderBlock {HTML} at (0,0) size 380x330
+        RenderBody {BODY} at (8,8) size 364x314 [bgcolor=#000000]
+    layer at (40,165) size 300x1
+      RenderVideo {VIDEO} at (40,164.50) size 300x1
+    layer at (40,165) size 300x1
+      RenderFlexibleBox {DIV} at (0,0) size 300x1
+        RenderBlock {DIV} at (0,-34) size 300x35
+    layer at (45,131) size 290x30
+      RenderFlexibleBox {DIV} at (5,0) size 290x30 [bgcolor=#141414CC]
+        RenderButton {INPUT} at (9,0) size 30x30
+        RenderSlider {INPUT} at (48,11) size 98.47x8
+          RenderFlexibleBox {DIV} at (0,0) size 98.47x8 [border: (1px solid #E6E6E659)]
+            RenderBlock {DIV} at (1,-8) size 110.47x24
+              RenderBlock {DIV} at (32.22,0) size 32x24
+        RenderFlexibleBox {DIV} at (161.47,0) size 25x30 [color=#FFFFFF]
+          RenderBlock (anonymous) at (0,0) size 25x30
+            RenderText {#text} at (0,7) size 25x16
+              text run at (0,7) width 25: "0:00"
+        RenderButton {INPUT} at (195.47,0) size 35x30
+        RenderSlider {INPUT} at (236.47,11) size 38.53x8
+          RenderFlexibleBox {DIV} at (0,0) size 38.53x8 [border: (1px solid #E6E6E659)]
+            RenderBlock {DIV} at (1,-8) size 50.53x24
+              RenderBlock {DIV} at (19.53,0) size 24x24