Always give RenderParts a RenderLayer.

LayoutTests/platform/linux/svg/custom/getsvgdocument-expected.txt

Index: LayoutTests/platform/linux/svg/custom/getsvgdocument-expected.txt
diff --git a/LayoutTests/platform/linux/svg/custom/getsvgdocument-expected.txt b/LayoutTests/platform/linux/svg/custom/getsvgdocument-expected.txt
index 3f17dbc22a318371e09d889565668f8152a84835..e65d858c16d059f351c516cb5cc10a7bd05df636 100644
--- a/LayoutTests/platform/linux/svg/custom/getsvgdocument-expected.txt
+++ b/LayoutTests/platform/linux/svg/custom/getsvgdocument-expected.txt
@@ -8,24 +8,26 @@ layer at (0,0) size 800x600
           text run at (0,0) width 771: "This tests to see if HTMLEmbedElement.getSVGDocument() and HTMLObjectElement.getSVGDocument() work. You should"
           text run at (0,20) width 243: "see SUCCESS printed twice below this:"
       RenderBlock (anonymous) at (0,56) size 784x60
-        RenderEmbeddedObject {EMBED} at (0,0) size 85x20
-          layer at (0,0) size 85x20
-            RenderView at (0,0) size 85x20
-          layer at (0,0) size 85x20
-            RenderSVGRoot {svg} at (0,0) size 85x20
-              RenderSVGRect {rect} at (0,0) size 85x20 [fill={[type=SOLID] [color=#008000]}] [x=0.00] [y=0.00] [width=85.00] [height=20.00]
-              RenderSVGText {text} at (5,1) size 69x19 contains 1 chunk(s)
-                RenderSVGInlineText {#text} at (0,0) size 69x19
-                  chunk 1 text run 1 at (5.00,16.00) startOffset 0 endOffset 7 width 69.00: "SUCCESS"
         RenderBR {BR} at (85,20) size 0x0
         RenderBR {BR} at (0,20) size 0x19
-        RenderEmbeddedObject {OBJECT} at (0,40) size 85x20
-          layer at (0,0) size 85x20
-            RenderView at (0,0) size 85x20
-          layer at (0,0) size 85x20
-            RenderSVGRoot {svg} at (0,0) size 85x20
-              RenderSVGRect {rect} at (0,0) size 85x20 [fill={[type=SOLID] [color=#008000]}] [x=0.00] [y=0.00] [width=85.00] [height=20.00]
-              RenderSVGText {text} at (5,1) size 69x19 contains 1 chunk(s)
-                RenderSVGInlineText {#text} at (0,0) size 69x19
-                  chunk 1 text run 1 at (5.00,16.00) startOffset 0 endOffset 7 width 69.00: "SUCCESS"
         RenderText {#text} at (0,0) size 0x0
+layer at (8,64) size 85x20
+  RenderEmbeddedObject {EMBED} at (0,0) size 85x20
+    layer at (0,0) size 85x20
+      RenderView at (0,0) size 85x20
+    layer at (0,0) size 85x20
+      RenderSVGRoot {svg} at (0,0) size 85x20
+        RenderSVGRect {rect} at (0,0) size 85x20 [fill={[type=SOLID] [color=#008000]}] [x=0.00] [y=0.00] [width=85.00] [height=20.00]
+        RenderSVGText {text} at (5,1) size 69x19 contains 1 chunk(s)
+          RenderSVGInlineText {#text} at (0,0) size 69x19
+            chunk 1 text run 1 at (5.00,16.00) startOffset 0 endOffset 7 width 69.00: "SUCCESS"
+layer at (8,104) size 85x20
+  RenderEmbeddedObject {OBJECT} at (0,40) size 85x20
+    layer at (0,0) size 85x20
+      RenderView at (0,0) size 85x20
+    layer at (0,0) size 85x20
+      RenderSVGRoot {svg} at (0,0) size 85x20
+        RenderSVGRect {rect} at (0,0) size 85x20 [fill={[type=SOLID] [color=#008000]}] [x=0.00] [y=0.00] [width=85.00] [height=20.00]
+        RenderSVGText {text} at (5,1) size 69x19 contains 1 chunk(s)
+          RenderSVGInlineText {#text} at (0,0) size 69x19
+            chunk 1 text run 1 at (5.00,16.00) startOffset 0 endOffset 7 width 69.00: "SUCCESS"