Move and rename RenderBR to LayoutBR.

LayoutTests/platform/mac/fast/forms/textarea-width-expected.txt

Index: LayoutTests/platform/mac/fast/forms/textarea-width-expected.txt
diff --git a/LayoutTests/platform/mac/fast/forms/textarea-width-expected.txt b/LayoutTests/platform/mac/fast/forms/textarea-width-expected.txt
index 3fc238ebe99d4a17e24bb8789f4277bae5b4a310..cee9c3aaa17768a87c1ca130e2bb93ec777b6198 100644
--- a/LayoutTests/platform/mac/fast/forms/textarea-width-expected.txt
+++ b/LayoutTests/platform/mac/fast/forms/textarea-width-expected.txt
@@ -8,7 +8,7 @@ layer at (0,0) size 800x600
           text run at (0,0) width 753: "This text area should be drawn with a reasonable width. To match IE, using GDI fonts it should wrap at 66 characters"
           text run at (0,18) width 581: "(after the X in the third set of digits). See https://bugs.webkit.org/show_bug.cgi?id=15312."
       RenderBlock (anonymous) at (0,36) size 784x264
-        RenderBR {BR} at (0,0) size 0x18
+        LayoutBR {BR} at (0,0) size 0x18
         RenderText {#text} at (0,0) size 0x0
 layer at (8,62) size 549x246 clip at (9,63) size 547x244
   LayoutTextControl {TEXTAREA} at (0,18) size 549x246 [color=#333333] [bgcolor=#FFFFFF] [border: (1px solid #333333)]
@@ -16,5 +16,5 @@ layer at (8,62) size 549x246 clip at (9,63) size 547x244
       RenderText {#text} at (0,0) size 540x24
         text run at (0,0) width 540: "1234567890abcdefghijABCDEFGHIJ1234567890abcdefghijABCDEFGHIJ12345X7890abcdefghijABCDEFGXIJ"
         text run at (0,12) width 180: "1234567890abcdefghijABCDEFGHIJ"
-      RenderBR {BR} at (179,22) size 1x0
-      RenderBR {BR} at (0,24) size 0x12
+      LayoutBR {BR} at (179,22) size 1x0
+      LayoutBR {BR} at (0,24) size 0x12