Move the SVG container code from rendering/svg to layout/svg.

LayoutTests/svg/filters/innershadow-expected.txt

 layer at (0,0) size 800x600
   RenderView at (0,0) size 800x600
 layer at (0,0) size 800x400
   RenderSVGRoot {svg} at (0,80) size 700x240
     LayoutSVGContainer {g} at (0,80) size 700x240 [transform={m=((2.00,0.00)(0.00,2.00)) t=(0.00,0.00)}]
       LayoutSVGContainer {use} at (0,80) size 240x240 [transform={m=((1.00,0.00)(0.00,1.00)) t=(10.00,150.00)}]
         [filter="ct"] LayoutSVGResourceFilter {filter} at (-10,-110) size 120x120
         LayoutSVGContainer {g} at (20,100) size 200x200
           LayoutSVGRect {rect} at (20,100) size 200x200 [fill={[type=SOLID] [color=#FF0000]}] [x=0.00] [y=-100.00] [width=100.00] [height=100.00]
           LayoutSVGRect {rect} at (34,114) size 186x186 [fill={[type=SOLID] [color=#008000]}] [x=7.00] [y=-93.00] [width=93.00] [height=93.00]
       LayoutSVGContainer {use} at (230,80) size 240x240 [transform={m=((1.00,0.00)(0.00,1.00)) t=(125.00,150.00)}]
         [filter="cm"] LayoutSVGResourceFilter {filter} at (-10,-110) size 120x120
         LayoutSVGContainer {g} at (250,100) size 200x200
           LayoutSVGRect {rect} at (250,100) size 200x200 [fill={[type=SOLID] [color=#FF0000]}] [x=0.00] [y=-100.00] [width=100.00] [height=100.00]
           LayoutSVGRect {rect} at (264,114) size 186x186 [fill={[type=SOLID] [color=#008000]}] [x=7.00] [y=-93.00] [width=93.00] [height=93.00]
       LayoutSVGContainer {use} at (460,80) size 240x240 [transform={m=((1.00,0.00)(0.00,1.00)) t=(240.00,150.00)}]
         [filter="ar"] LayoutSVGResourceFilter {filter} at (-10,-110) size 120x120
         LayoutSVGContainer {g} at (480,100) size 200x200
           LayoutSVGRect {rect} at (480,100) size 200x200 [fill={[type=SOLID] [color=#FF0000]}] [x=0.00] [y=-100.00] [width=100.00] [height=100.00]
           LayoutSVGRect {rect} at (494,114) size 186x186 [fill={[type=SOLID] [color=#008000]}] [x=7.00] [y=-93.00] [width=93.00] [height=93.00]
-    RenderSVGHiddenContainer {defs} at (0,0) size 0x0
+    LayoutSVGHiddenContainer {defs} at (0,0) size 0x0
       LayoutSVGContainer {g} at (0,0) size 0x0
         LayoutSVGRect {rect} at (0,0) size 0x0 [fill={[type=SOLID] [color=#FF0000]}] [x=0.00] [y=-100.00] [width=100.00] [height=100.00]
         LayoutSVGRect {rect} at (0,0) size 0x0 [fill={[type=SOLID] [color=#008000]}] [x=7.00] [y=-93.00] [width=93.00] [height=93.00]
       LayoutSVGResourceFilter {filter} [id="ct"] [filterUnits=objectBoundingBox] [primitiveUnits=userSpaceOnUse]
         [feComposite operation="ATOP"]
           [feComponentTransfer 
               {red: type="LINEAR" slope="0.00" intercept="0.00" amplitude="1.00" exponent="1.00" offset="0.00"}
               {green: type="LINEAR" slope="0.00" intercept="0.00" amplitude="1.00" exponent="1.00" offset="0.00"}
               {blue: type="LINEAR" slope="0.00" intercept="0.00" amplitude="1.00" exponent="1.00" offset="0.00"}
               {alpha: type="LINEAR" slope="-1.00" intercept="1.00" amplitude="1.00" exponent="1.00" offset="0.00"}]
@@ skipping 16 matching lines @@
               {blue: type="LINEAR" slope="0.00" intercept="0.00" amplitude="1.00" exponent="1.00" offset="0.00"}
               {alpha: type="UNKNOWN" slope="0.00" intercept="0.00" amplitude="0.00" exponent="0.00" offset="0.00"}]
             [feComposite operation="ARITHMETIC" k1="0.00" k2="-1.00" k3="0.00" k4="1.00"]
               [feGaussianBlur stdDeviation="1.00, 1.00"]
                 [feOffset dx="10.00" dy="10.00"]
                   [SourceGraphic]
               [feGaussianBlur stdDeviation="1.00, 1.00"]
                 [feOffset dx="10.00" dy="10.00"]
                   [SourceGraphic]
           [SourceGraphic]