Move and rename RenderBR to LayoutBR.

LayoutTests/platform/linux/fast/forms/button-align-expected.txt

Index: LayoutTests/platform/linux/fast/forms/button-align-expected.txt
diff --git a/LayoutTests/platform/linux/fast/forms/button-align-expected.txt b/LayoutTests/platform/linux/fast/forms/button-align-expected.txt
index 020d56d2662451ec934afb9a993fb88c33ce465a..f90800cd2d12f021e916afb07a3a092346f28273 100644
--- a/LayoutTests/platform/linux/fast/forms/button-align-expected.txt
+++ b/LayoutTests/platform/linux/fast/forms/button-align-expected.txt
@@ -13,21 +13,21 @@ layer at (0,0) size 800x600
               text run at (47,0) width 190: "This is should be center justified."
         RenderText {#text} at (300,1) size 4x19
           text run at (300,1) width 4: " "
-        RenderBR {BR} at (0,0) size 0x0
+        LayoutBR {BR} at (0,0) size 0x0
         RenderButton {BUTTON} at (0,22) size 300x22 [bgcolor=#C0C0C0] [border: (2px outset #C0C0C0)]
           RenderBlock (anonymous) at (8,3) size 284x16
             RenderText {#text} at (47,0) size 190x16
               text run at (47,0) width 190: "This is should be center justified."
         RenderText {#text} at (300,23) size 4x19
           text run at (300,23) width 4: " "
-        RenderBR {BR} at (0,0) size 0x0
+        LayoutBR {BR} at (0,0) size 0x0
         RenderButton {BUTTON} at (0,44) size 300x22 [bgcolor=#C0C0C0] [border: (2px outset #C0C0C0)]
           RenderBlock (anonymous) at (8,3) size 284x16
             RenderText {#text} at (47,0) size 190x16
               text run at (47,0) width 190: "This is should be center justified."
         RenderText {#text} at (300,45) size 4x19
           text run at (300,45) width 4: " "
-        RenderBR {BR} at (0,0) size 0x0
+        LayoutBR {BR} at (0,0) size 0x0
         RenderButton {BUTTON} at (0,66) size 300x22 [bgcolor=#C0C0C0] [border: (2px outset #C0C0C0)]
           RenderBlock (anonymous) at (8,3) size 284x16
             RenderText {#text} at (47,0) size 190x16