Always give RenderParts a RenderLayer.

LayoutTests/platform/linux/svg/in-html/by-reference-expected.txt

Index: LayoutTests/platform/linux/svg/in-html/by-reference-expected.txt
diff --git a/LayoutTests/platform/linux/svg/in-html/by-reference-expected.txt b/LayoutTests/platform/linux/svg/in-html/by-reference-expected.txt
index b391810c1521ef5b897a9955ce398a8f09aa298e..bc8e115b16a24186dc662a764dba96fec85fdede 100644
--- a/LayoutTests/platform/linux/svg/in-html/by-reference-expected.txt
+++ b/LayoutTests/platform/linux/svg/in-html/by-reference-expected.txt
@@ -4,37 +4,41 @@ layer at (0,0) size 800x400
   RenderBlock {HTML} at (0,0) size 800x400
     RenderBody {BODY} at (0,0) size 800x400
       RenderBlock {DIV} at (0,0) size 400x400 [bgcolor=#00FF00]
-        RenderEmbeddedObject {OBJECT} at (0,50) size 50x50
-          layer at (0,0) size 50x50
-            RenderView at (0,0) size 50x50
-          layer at (0,0) size 50x50
-            RenderSVGRoot {svg} at (0,0) size 0x0
         RenderText {#text} at (50,85) size 4x19
           text run at (50,85) width 4: " "
-        RenderEmbeddedObject {EMBED} at (54,50) size 50x50
-          layer at (0,0) size 50x50
-            RenderView at (0,0) size 50x50
-          layer at (0,0) size 50x50
-            RenderSVGRoot {svg} at (0,0) size 0x0
         RenderText {#text} at (104,85) size 4x19
           text run at (104,85) width 4: " "
         RenderText {#text} at (208,85) size 4x19
           text run at (208,85) width 4: " "
-        RenderEmbeddedObject {OBJECT} at (212,50) size 50x50
-          layer at (0,0) size 50x50
-            RenderView at (0,0) size 50x50
-          layer at (0,0) size 50x50
-            RenderSVGRoot {svg} at (0,0) size 0x0
         RenderText {#text} at (262,85) size 4x19
           text run at (262,85) width 4: " "
-        RenderEmbeddedObject {OBJECT} at (266,50) size 50x50
-          layer at (0,0) size 50x50
-            RenderView at (0,0) size 50x50
-          layer at (0,0) size 50x50
-            RenderSVGRoot {svg} at (0,0) size 0x0
+layer at (0,50) size 50x50
+  RenderEmbeddedObject {OBJECT} at (0,50) size 50x50
+    layer at (0,0) size 50x50
+      RenderView at (0,0) size 50x50
+    layer at (0,0) size 50x50
+      RenderSVGRoot {svg} at (0,0) size 0x0
+layer at (54,50) size 50x50
+  RenderEmbeddedObject {EMBED} at (54,50) size 50x50
+    layer at (0,0) size 50x50
+      RenderView at (0,0) size 50x50
+    layer at (0,0) size 50x50
+      RenderSVGRoot {svg} at (0,0) size 0x0
 layer at (108,0) size 100x100
   RenderPartObject {IFRAME} at (108,0) size 100x100
     layer at (0,0) size 100x100
       RenderView at (0,0) size 100x100
     layer at (0,0) size 50x50
       RenderSVGRoot {svg} at (0,0) size 0x0
+layer at (212,50) size 50x50
+  RenderEmbeddedObject {OBJECT} at (212,50) size 50x50
+    layer at (0,0) size 50x50
+      RenderView at (0,0) size 50x50
+    layer at (0,0) size 50x50
+      RenderSVGRoot {svg} at (0,0) size 0x0
+layer at (266,50) size 50x50
+  RenderEmbeddedObject {OBJECT} at (266,50) size 50x50
+    layer at (0,0) size 50x50
+      RenderView at (0,0) size 50x50
+    layer at (0,0) size 50x50
+      RenderSVGRoot {svg} at (0,0) size 0x0