Move and rename RenderBR to LayoutBR.

LayoutTests/platform/mac/media/video-zoom-expected.txt

Index: LayoutTests/platform/mac/media/video-zoom-expected.txt
diff --git a/LayoutTests/platform/mac/media/video-zoom-expected.txt b/LayoutTests/platform/mac/media/video-zoom-expected.txt
index 09fca552a04dc38f813829f880ce439783d6b321..a8e3ab969606141cc60849f64ad30bb688d71fec 100644
--- a/LayoutTests/platform/mac/media/video-zoom-expected.txt
+++ b/LayoutTests/platform/mac/media/video-zoom-expected.txt
@@ -9,14 +9,14 @@ layer at (0,0) size 785x844 backgroundClip at (0,0) size 785x600 clip at (0,0) s
       RenderBlock (anonymous) at (0,34) size 769x372
         RenderText {#text} at (0,354) size 4x18
           text run at (0,354) width 4: " "
-        RenderBR {BR} at (492,368) size 0x0
+        LayoutBR {BR} at (492,368) size 0x0
       RenderBlock {P} at (0,422) size 769x18
         RenderText {#text} at (0,0) size 309x18
           text run at (0,0) width 309: "150% zoom, without width and height attributes"
       RenderBlock (anonymous) at (0,456) size 769x372
         RenderText {#text} at (0,354) size 4x18
           text run at (0,354) width 4: " "
-        RenderBR {BR} at (492,368) size 0x0
+        LayoutBR {BR} at (492,368) size 0x0
 layer at (12,42) size 488x368
   LayoutVideo {VIDEO} at (4,0) size 488x368 [border: (4px solid #FF0000)]
 layer at (12,464) size 488x368 backgroundClip at (0,0) size 785x600 clip at (0,0) size 785x600 outlineClip at (0,0) size 785x600