Move and rename RenderBR to LayoutBR.

LayoutTests/platform/mac/fast/css/layerZOrderCrash-expected.txt

Index: LayoutTests/platform/mac/fast/css/layerZOrderCrash-expected.txt
diff --git a/LayoutTests/platform/mac/fast/css/layerZOrderCrash-expected.txt b/LayoutTests/platform/mac/fast/css/layerZOrderCrash-expected.txt
index 8f4ec73506ad301e72bec9e49477add43cad2b78..2ec5dd54b0dc8eb71afc642d13c4bcd799f3df36 100644
--- a/LayoutTests/platform/mac/fast/css/layerZOrderCrash-expected.txt
+++ b/LayoutTests/platform/mac/fast/css/layerZOrderCrash-expected.txt
@@ -6,7 +6,7 @@ layer at (0,0) size 800x600
       RenderBlock (anonymous) at (0,0) size 784x18
         RenderText {#text} at (0,0) size 631x18
           text run at (0,0) width 631: "To reproduce this bug outside of DumpRenderTree, click the link below. If broken, we will crash. "
-        RenderBR {BR} at (630,14) size 1x0
+        LayoutBR {BR} at (630,14) size 1x0
 layer at (8,26) size 60x88
   LayoutTable {TABLE} at (0,18) size 60x88
     LayoutTableSection {TBODY} at (0,0) size 60x88
@@ -24,11 +24,11 @@ layer at (11,51) size 54x60
         LayoutTableCell {TD} at (2,2) size 50x56 [r=0 c=0 rs=1 cs=1]
           RenderText {#text} at (1,1) size 48x18
             text run at (1,1) width 48: "content"
-          RenderBR {BR} at (48,15) size 1x0
+          LayoutBR {BR} at (48,15) size 1x0
           RenderText {#text} at (1,19) size 48x18
             text run at (1,19) width 48: "content"
-          RenderBR {BR} at (48,33) size 1x0
+          LayoutBR {BR} at (48,33) size 1x0
           RenderText {#text} at (1,37) size 48x18
             text run at (1,37) width 48: "content"
-          RenderBR {BR} at (48,51) size 1x0
+          LayoutBR {BR} at (48,51) size 1x0
 caret: position 5 of child 0 {#text} of body