Move and rename RenderBR to LayoutBR.

LayoutTests/platform/win-xp/tables/mozilla/bugs/bug46368-1-expected.txt

 layer at (0,0) size 800x600
   RenderView at (0,0) size 800x600
 layer at (0,0) size 800x600
   RenderBlock {HTML} at (0,0) size 800x600
     RenderBody {BODY} at (8,8) size 784x584
       LayoutTable {TABLE} at (0,0) size 784x117 [bgcolor=#00FFFF] [border: (1px outset #808080)]
         LayoutTableSection {TBODY} at (1,1) size 782x115
           LayoutTableRow {TR} at (0,2) size 782x111
             LayoutTableCell {TD} at (2,2) size 455x111 [border: (1px inset #808080)] [r=0 c=0 rs=1 cs=1]
               LayoutTable {TABLE} at (2,2) size 451x107 [bgcolor=#FF00FF] [border: (1px outset #808080)]
                 LayoutTableSection {TBODY} at (1,1) size 449x105
                   LayoutTableRow {TR} at (0,2) size 449x101
                     LayoutTableCell {TD} at (2,2) size 445x101 [border: (1px inset #808080)] [r=0 c=0 rs=1 cs=1]
                       RenderText {#text} at (2,2) size 188x19
                         text run at (2,2) width 188: "Mozilla To Be Dually-Licensed"
-                      RenderBR {BR} at (190,17) size 0x0
+                      LayoutBR {BR} at (190,17) size 0x0
                       RenderText {#text} at (2,35) size 197x19
                         text run at (2,35) width 197: "Plans are underway to make the "
                       RenderInline {FONT} at (0,0) size 99x36 [color=#0000FF]
                         RenderText {#text} at (199,22) size 99x36
                           text run at (199,22) width 99: "Mozilla"
                       RenderText {#text} at (298,35) size 435x63
                         text run at (298,35) width 139: " code available under a"
                         text run at (2,59) width 146: "dual MPL/GPL license. "
                         text run at (148,59) width 230: "See the for more info. We're gathering"
                         text run at (2,79) width 243: "contributor input now, in the newsgroup."
-                      RenderBR {BR} at (245,94) size 0x0
+                      LayoutBR {BR} at (245,94) size 0x0
             LayoutTableCell {TD} at (459,25) size 321x64 [border: (1px inset #808080)] [r=0 c=1 rs=1 cs=1]
               RenderText {#text} at (2,2) size 303x59
                 text run at (2,2) width 251: "This status update contains information on"
                 text run at (2,22) width 303: "MailNews, XML/DOM, XPToolkit, Architecture,"
                 text run at (2,42) width 192: "Bidi, Necko/Imglib, and more..."
       RenderBlock (anonymous) at (0,117) size 784x42
-        RenderBR {BR} at (0,0) size 0x19
+        LayoutBR {BR} at (0,0) size 0x19
         RenderButton {INPUT} at (0,20) size 56x22 [bgcolor=#C0C0C0] [border: (2px outset #C0C0C0)]
           RenderBlock (anonymous) at (8,3) size 40x16
             RenderText {#text} at (0,0) size 40x16
               text run at (0,0) width 40: "Reload"
         RenderText {#text} at (56,21) size 8x19
           text run at (56,21) width 8: "  "
         RenderButton {INPUT} at (64,20) size 90x22 [bgcolor=#C0C0C0] [border: (2px outset #C0C0C0)]
           RenderBlock (anonymous) at (8,3) size 74x16
             RenderText {#text} at (0,0) size 74x16
               text run at (0,0) width 74: "Change Font"
         RenderText {#text} at (154,21) size 8x19
           text run at (154,21) width 8: "  "
         LayoutTextControl {INPUT} at (162,20) size 153x22 [bgcolor=#FFFFFF] [border: (2px inset #EEEEEE)]
         RenderText {#text} at (0,0) size 0x0
 layer at (172,148) size 149x16
   RenderBlock {DIV} at (2,3) size 149x16
     RenderText {#text} at (0,0) size 7x16
       text run at (0,0) width 7: "6"