Move and rename RenderBR to LayoutBR.

LayoutTests/platform/mac/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 784x111 [bgcolor=#00FFFF] [border: (1px outset #808080)]
         LayoutTableSection {TBODY} at (1,1) size 782x109
           LayoutTableRow {TR} at (0,2) size 782x105
             LayoutTableCell {TD} at (2,2) size 454x105 [border: (1px inset #808080)] [r=0 c=0 rs=1 cs=1]
               LayoutTable {TABLE} at (2,2) size 450x101 [bgcolor=#FF00FF] [border: (1px outset #808080)]
                 LayoutTableSection {TBODY} at (1,1) size 448x99
                   LayoutTableRow {TR} at (0,2) size 448x95
                     LayoutTableCell {TD} at (2,2) size 444x95 [border: (1px inset #808080)] [r=0 c=0 rs=1 cs=1]
                       RenderText {#text} at (2,2) size 204x18
                         text run at (2,2) width 204: "Mozilla To Be Dually-Licensed"
-                      RenderBR {BR} at (205,16) size 1x0
+                      LayoutBR {BR} at (205,16) size 1x0
                       RenderText {#text} at (2,35) size 208x18
                         text run at (2,35) width 208: "Plans are underway to make the "
                       RenderInline {FONT} at (0,0) size 101x37 [color=#0000FF]
                         RenderText {#text} at (209,20) size 101x37
                           text run at (209,20) width 101: "Mozilla"
                       RenderText {#text} at (309,35) size 404x58
                         text run at (309,35) width 97: " code available"
                         text run at (2,57) width 52: "under a "
                         text run at (53,57) width 157: "dual MPL/GPL license. "
                         text run at (209,57) width 182: "See the for more info. We're"
                         text run at (2,75) width 327: "gathering contributor input now, in the newsgroup."
-                      RenderBR {BR} at (328,89) size 1x0
+                      LayoutBR {BR} at (328,89) size 1x0
             LayoutTableCell {TD} at (458,25) size 322x58 [border: (1px inset #808080)] [r=0 c=1 rs=1 cs=1]
               RenderText {#text} at (2,2) size 293x54
                 text run at (2,2) width 273: "This status update contains information on"
                 text run at (2,20) width 232: "MailNews, XML/DOM, XPToolkit,"
                 text run at (2,38) width 293: "Architecture, Bidi, Necko/Imglib, and more..."
       RenderBlock (anonymous) at (0,111) size 784x37
-        RenderBR {BR} at (0,0) size 0x18
+        LayoutBR {BR} at (0,0) size 0x18
         RenderButton {INPUT} at (0,19) size 52.03x18 [bgcolor=#C0C0C0]
           RenderBlock (anonymous) at (8,2) size 36.03x13
             RenderText {#text} at (0,0) size 37x13
               text run at (0,0) width 37: "Reload"
         RenderText {#text} at (52,18) size 9x18
           text run at (52,18) width 9: "  "
         RenderButton {INPUT} at (60.03,19) size 83.41x18 [bgcolor=#C0C0C0]
           RenderBlock (anonymous) at (8,2) size 67.41x13
             RenderText {#text} at (0,0) size 68x13
               text run at (0,0) width 68: "Change Font"
         RenderText {#text} at (143,18) size 9x18
           text run at (143,18) width 9: "  "
         LayoutTextControl {INPUT} at (151.44,18) size 123x19 [bgcolor=#FFFFFF] [border: (2px inset #EEEEEE)]
         RenderText {#text} at (0,0) size 0x0
 layer at (162,140) size 117x13
   RenderBlock {DIV} at (3,3) size 117x13
     RenderText {#text} at (0,0) size 7x13
       text run at (0,0) width 7: "6"