Move and rename RenderBR to LayoutBR.

LayoutTests/platform/mac/tables/mozilla/bugs/bug46924-expected.txt

Index: LayoutTests/platform/mac/tables/mozilla/bugs/bug46924-expected.txt
diff --git a/LayoutTests/platform/mac/tables/mozilla/bugs/bug46924-expected.txt b/LayoutTests/platform/mac/tables/mozilla/bugs/bug46924-expected.txt
index 9781ce48880a04e1864cd301b86618265ce30c47..f207a15b900cf49dcdb6648b6f11e42edf0ed49e 100644
--- a/LayoutTests/platform/mac/tables/mozilla/bugs/bug46924-expected.txt
+++ b/LayoutTests/platform/mac/tables/mozilla/bugs/bug46924-expected.txt
@@ -16,7 +16,7 @@ layer at (0,0) size 800x256
           LayoutTableRow {TR} at (0,2) size 782x22 [bgcolor=#C0C0C0]
             LayoutTableCell {TD} at (2,2) size 778x22 [border: (1px inset #808080)] [r=0 c=0 rs=1 cs=1]
       RenderBlock (anonymous) at (0,70) size 784x18
-        RenderBR {BR} at (0,0) size 0x18
+        LayoutBR {BR} at (0,0) size 0x18
       RenderBlock {DIV} at (0,88) size 784x18
         RenderText {#text} at (0,0) size 305x18
           text run at (0,0) width 305: "For comparison: The same table without a tfoot"
@@ -38,7 +38,7 @@ layer at (0,0) size 800x256
               RenderText {#text} at (667,2) size 109x18
                 text run at (667,2) width 109: "This is the footer"
       RenderBlock (anonymous) at (0,222) size 784x18
-        RenderBR {BR} at (0,0) size 0x18
+        LayoutBR {BR} at (0,0) size 0x18
 layer at (13,31) size 387x18
   RenderBlock (relative positioned) {DIV} at (2,2) size 387x18 [bgcolor=#FF0000]
     RenderText {#text} at (109,0) size 278x18