Move and rename RenderBR to LayoutBR.

LayoutTests/platform/linux/fast/dom/HTMLTableElement/colSpan-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
       RenderBlock {P} at (0,0) size 784x20
         RenderText {#text} at (0,0) size 160x19
           text run at (0,0) width 160: "Tests: the colspan attribute"
-        RenderBR {BR} at (160,15) size 0x0
+        LayoutBR {BR} at (160,15) size 0x0
       RenderBlock {P} at (0,36) size 784x80
         RenderText {#text} at (0,0) size 68x19
           text run at (0,0) width 68: "Conditions:"
-        RenderBR {BR} at (68,15) size 0x0
+        LayoutBR {BR} at (68,15) size 0x0
         RenderText {#text} at (0,20) size 767x59
           text run at (0,20) width 619: "The colSpan attribute specifies the number of columns spanned by the current cell. The default value of "
           text run at (619,20) width 148: "this attribute is one (\"1\")."
           text run at (0,40) width 446: "The value zero (\"0\") means that the cell spans all columns from the current "
           text run at (446,40) width 276: "column to the last column of the column group"
           text run at (0,60) width 259: "(COLGROUP) in which the cell is defined."
       RenderBlock {P} at (0,132) size 784x60
         RenderText {#text} at (0,0) size 775x59
           text run at (0,0) width 775: "The first table tests the default value of one, and an input of 7, which is within the normal range of expect input. The first column in"
           text run at (0,20) width 604: "the first row should span only column \"one\" and the second cell should span all of the other columns. "
           text run at (604,20) width 156: "The second table tests the"
           text run at (0,40) width 397: "zero value. \"Just A\" should span \"A\" and \"Just B\" should span \"B.\""
       RenderBlock {HR} at (0,208) size 784x2 [border: (1px inset #EEEEEE)]
       RenderBlock (anonymous) at (0,218) size 784x20
-        RenderBR {BR} at (0,0) size 0x19
+        LayoutBR {BR} at (0,0) size 0x19
       LayoutTable {TABLE} at (0,238) size 255x76 [border: (1px outset #808080)]
         RenderBlock {CAPTION} at (0,0) size 255x20
           RenderText {#text} at (27,0) size 201x19
             text run at (27,0) width 201: "Testing Default and Regular Input"
         LayoutTableSection {TBODY} at (1,21) size 253x54
           LayoutTableRow {TR} at (0,2) size 253x24
             LayoutTableCell {TD} at (2,2) size 31x24 [border: (1px inset #808080)] [r=0 c=0 rs=1 cs=1]
               RenderText {#text} at (2,2) size 27x19
                 text run at (2,2) width 27: "First"
             LayoutTableCell {TD} at (35,2) size 216x24 [border: (1px inset #808080)] [r=0 c=1 rs=1 cs=7]
@@ skipping 18 matching lines @@
             LayoutTableCell {TD} at (157,28) size 20x24 [border: (1px inset #808080)] [r=1 c=5 rs=1 cs=1]
               RenderText {#text} at (2,2) size 16x19
                 text run at (2,2) width 16: "six"
             LayoutTableCell {TD} at (179,28) size 38x24 [border: (1px inset #808080)] [r=1 c=6 rs=1 cs=1]
               RenderText {#text} at (2,2) size 34x19
                 text run at (2,2) width 34: "seven"
             LayoutTableCell {TD} at (219,28) size 32x24 [border: (1px inset #808080)] [r=1 c=7 rs=1 cs=1]
               RenderText {#text} at (2,2) size 28x19
                 text run at (2,2) width 28: "eight"
       RenderBlock (anonymous) at (0,314) size 784x20
-        RenderBR {BR} at (0,0) size 0x19
+        LayoutBR {BR} at (0,0) size 0x19
       LayoutTable {TABLE} at (0,334) size 189x76 [border: (1px outset #808080)]
         RenderBlock {CAPTION} at (0,0) size 189x20
           RenderText {#text} at (15,0) size 159x19
             text run at (15,0) width 159: "Testing Zero Special Case"
         LayoutTableSection {TBODY} at (1,21) size 187x54
           LayoutTableRow {TR} at (0,2) size 187x24
             LayoutTableCell {TD} at (2,2) size 42x24 [border: (1px inset #808080)] [r=0 c=0 rs=1 cs=1]
               RenderText {#text} at (2,2) size 38x19
                 text run at (2,2) width 38: "Just A"
             LayoutTableCell {TD} at (46,2) size 41x24 [border: (1px inset #808080)] [r=0 c=1 rs=1 cs=1]
@@ skipping 17 matching lines @@
                 text run at (2,2) width 9: "E"
             LayoutTableCell {TD} at (138,28) size 13x24 [border: (1px inset #808080)] [r=1 c=5 rs=1 cs=1]
               RenderText {#text} at (2,2) size 9x19
                 text run at (2,2) width 9: "F"
             LayoutTableCell {TD} at (153,28) size 15x24 [border: (1px inset #808080)] [r=1 c=6 rs=1 cs=1]
               RenderText {#text} at (2,2) size 11x19
                 text run at (2,2) width 11: "G"
             LayoutTableCell {TD} at (170,28) size 15x24 [border: (1px inset #808080)] [r=1 c=7 rs=1 cs=1]
               RenderText {#text} at (2,2) size 11x19
                 text run at (2,2) width 11: "H"