Move and rename RenderBR to LayoutBR.

LayoutTests/platform/linux/svg/wicd/rightsizing-grid-expected.txt

 layer at (0,0) size 800x600 clip at (0,0) size 785x600 scrollHeight 1449
   RenderView at (0,0) size 800x600
 layer at (0,0) size 785x1449 backgroundClip at (0,0) size 785x600 clip at (0,0) size 785x600 outlineClip at (0,0) size 785x600
   RenderBlock {html} at (0,0) size 785x1449.14
     RenderBody {body} at (8,8) size 769x0
       RenderBlock (floating) {div} at (0,0) size 769x1441.14
         RenderBlock {h1} at (0,21.44) size 769x37
           RenderText {#text} at (0,0) size 443x36
             text run at (0,0) width 443: "SVG grid with percentage width"
         RenderBlock {h4} at (0,79.88) size 769x20
           RenderText {#text} at (0,0) size 146x19
             text run at (0,0) width 146: "WICD Core 1.0 #20-3"
         RenderBlock {p} at (0,121.14) size 769x0
           RenderBlock (floating) {div} at (256.30,128) size 256.30x448
-            RenderBR {br} at (256,0) size 1x19
+            LayoutBR {br} at (256,0) size 1x19
           RenderBlock (floating) {div} at (512.59,128) size 256.30x448
           RenderBlock (floating) {div} at (384.50,704) size 384.50x192
           RenderBlock (floating) {div} at (0,896) size 384.50x192
           RenderBlock (floating) {div} at (384.50,1024) size 384.50x128
         RenderBlock {p} at (0,121.14) size 769x596 [color=#FFFFFF]
-          RenderBR {br} at (769,0) size 0x19
+          LayoutBR {br} at (769,0) size 0x19
           RenderText {#text} at (640,576) size 9x19
             text run at (640,576) width 9: ".."
         RenderBlock {p} at (0,733.14) size 769x580
           RenderText {#text} at (640,0) size 760x579
             text run at (640,0) width 115: "Above, you should"
             text run at (640,20) width 95: "see a grid of 17"
             text run at (640,40) width 120: "SVG child elements"
             text run at (640,60) width 113: "sticked together to"
             text run at (0,540) width 148: "build one rectangle grid. "
             text run at (148,540) width 584: "You should be able to resize your browser window and the grid rendering should adjust to it. The"
@@ skipping 11 matching lines @@
           RenderInline {a} at (0,0) size 18x19 [color=#0000EE]
             RenderText {#text} at (432,560) size 18x19
               text run at (432,560) width 18: "big"
           RenderText {#text} at (450,560) size 4x19
             text run at (450,560) width 4: "."
         RenderBlock {p} at (0,1329.14) size 769x40
           RenderText {#text} at (0,0) size 755x39
             text run at (0,0) width 755: "The test is successful, if all SVG elements resize exacly dependend on the width of the browser window, but keep their aspect"
             text run at (0,20) width 553: "ratio and relative position. The complete grid should always show a perfect rectangle object."
         RenderBlock {p} at (0,1385.14) size 769x40
-          RenderBR {br} at (0,0) size 0x19
+          LayoutBR {br} at (0,0) size 0x19
           RenderInline {a} at (0,0) size 32x19 [color=#0000EE]
             RenderText {#text} at (0,20) size 32x19
               text run at (0,20) width 32: "Back"
 layer at (8,129) size 385x128
   LayoutEmbeddedObject {object} at (0,0) size 384.50x128
     layer at (0,0) size 385x128
       RenderView at (0,0) size 385x128
     layer at (0,0) size 385x128
       RenderSVGRoot {svg} at (0,0) size 385x128
         LayoutSVGHiddenContainer {defs} at (0,0) size 0x0
@@ skipping 248 matching lines @@
     layer at (0,0) size 96x128
       RenderSVGRoot {svg} at (0,0) size 96x128
         LayoutSVGHiddenContainer {defs} at (0,0) size 0x0
           LayoutSVGResourceLinearGradient {linearGradient} [id="surface"] [gradientUnits=objectBoundingBox] [start=(1,0)] [end=(1,1)]
             RenderSVGGradientStop {stop} [offset=0.00] [color=#FFFFFF]
             RenderSVGGradientStop {stop} [offset=1.00] [color=#FFEEAA]
         LayoutSVGRect {rect} at (0,0) size 96x128 [stroke={[type=SOLID] [color=#FFCC33] [stroke width=2.00]}] [fill={[type=LINEAR-GRADIENT] [id="surface"]}] [x=1.00] [y=1.00] [width=28.00] [height=38.00]
         LayoutSVGText {text} at (8,8) size 14x24 contains 1 chunk(s)
           LayoutSVGInlineText {#text} at (0,0) size 13x23
             chunk 1 (middle anchor) text run 1 at (8.75,27.00) startOffset 0 endOffset 1 width 12.50: "T"