Move and rename RenderBR to LayoutBR.

LayoutTests/platform/win-xp/editing/input/reveal-caret-of-multiline-contenteditable-expected.txt

 layer at (0,0) size 800x600
   RenderView at (0,0) size 800x600
 layer at (0,0) size 800x238
   RenderBlock {HTML} at (0,0) size 800x238
     RenderBody {BODY} at (8,8) size 784x222
       RenderBlock {DIV} at (0,0) size 784x20
         RenderText {#text} at (0,0) size 568x19
           text run at (0,0) width 568: "When the caret is scrolled out, on starting typing it must be brought to the center of the control."
 layer at (8,28) size 784x202 clip at (9,29) size 767x185 scrollY 277.00 scrollHeight 620
   RenderBlock {DIV} at (0,20) size 784x202 [border: (1px solid #000000)]
     RenderText {#text} at (1,1) size 16x19
       text run at (1,1) width 16: "00"
-    RenderBR {BR} at (17,1) size 0x19
+    LayoutBR {BR} at (17,1) size 0x19
     RenderText {#text} at (1,21) size 16x19
       text run at (1,21) width 16: "01"
-    RenderBR {BR} at (17,21) size 0x19
+    LayoutBR {BR} at (17,21) size 0x19
     RenderText {#text} at (1,41) size 16x19
       text run at (1,41) width 16: "02"
-    RenderBR {BR} at (17,41) size 0x19
+    LayoutBR {BR} at (17,41) size 0x19
     RenderText {#text} at (1,61) size 16x19
       text run at (1,61) width 16: "03"
-    RenderBR {BR} at (17,61) size 0x19
+    LayoutBR {BR} at (17,61) size 0x19
     RenderText {#text} at (1,81) size 16x19
       text run at (1,81) width 16: "04"
-    RenderBR {BR} at (17,81) size 0x19
+    LayoutBR {BR} at (17,81) size 0x19
     RenderText {#text} at (1,101) size 16x19
       text run at (1,101) width 16: "05"
-    RenderBR {BR} at (17,101) size 0x19
+    LayoutBR {BR} at (17,101) size 0x19
     RenderText {#text} at (1,121) size 16x19
       text run at (1,121) width 16: "06"
-    RenderBR {BR} at (17,121) size 0x19
+    LayoutBR {BR} at (17,121) size 0x19
     RenderText {#text} at (1,141) size 16x19
       text run at (1,141) width 16: "07"
-    RenderBR {BR} at (17,141) size 0x19
+    LayoutBR {BR} at (17,141) size 0x19
     RenderText {#text} at (1,161) size 16x19
       text run at (1,161) width 16: "08"
-    RenderBR {BR} at (17,161) size 0x19
+    LayoutBR {BR} at (17,161) size 0x19
     RenderText {#text} at (1,181) size 16x19
       text run at (1,181) width 16: "09"
-    RenderBR {BR} at (17,181) size 0x19
+    LayoutBR {BR} at (17,181) size 0x19
     RenderText {#text} at (1,201) size 16x19
       text run at (1,201) width 16: "10"
-    RenderBR {BR} at (17,201) size 0x19
+    LayoutBR {BR} at (17,201) size 0x19
     RenderText {#text} at (1,221) size 16x19
       text run at (1,221) width 16: "11"
-    RenderBR {BR} at (17,221) size 0x19
+    LayoutBR {BR} at (17,221) size 0x19
     RenderText {#text} at (1,241) size 16x19
       text run at (1,241) width 16: "12"
-    RenderBR {BR} at (17,241) size 0x19
+    LayoutBR {BR} at (17,241) size 0x19
     RenderText {#text} at (1,261) size 16x19
       text run at (1,261) width 16: "13"
-    RenderBR {BR} at (17,261) size 0x19
+    LayoutBR {BR} at (17,261) size 0x19
     RenderText {#text} at (1,281) size 16x19
       text run at (1,281) width 16: "14"
-    RenderBR {BR} at (17,281) size 0x19
+    LayoutBR {BR} at (17,281) size 0x19
     RenderText {#text} at (1,301) size 16x19
       text run at (1,301) width 16: "15"
-    RenderBR {BR} at (17,301) size 0x19
+    LayoutBR {BR} at (17,301) size 0x19
     RenderText {#text} at (1,321) size 16x19
       text run at (1,321) width 16: "16"
-    RenderBR {BR} at (17,321) size 0x19
+    LayoutBR {BR} at (17,321) size 0x19
     RenderText {#text} at (1,341) size 16x19
       text run at (1,341) width 16: "17"
-    RenderBR {BR} at (17,341) size 0x19
+    LayoutBR {BR} at (17,341) size 0x19
     RenderText {#text} at (1,361) size 25x19
       text run at (1,361) width 25: ">18"
-    RenderBR {BR} at (26,361) size 0x19
+    LayoutBR {BR} at (26,361) size 0x19
     RenderText {#text} at (1,381) size 16x19
       text run at (1,381) width 16: "19"
-    RenderBR {BR} at (17,381) size 0x19
+    LayoutBR {BR} at (17,381) size 0x19
     RenderText {#text} at (1,401) size 16x19
       text run at (1,401) width 16: "20"
-    RenderBR {BR} at (17,401) size 0x19
+    LayoutBR {BR} at (17,401) size 0x19
     RenderText {#text} at (1,421) size 16x19
       text run at (1,421) width 16: "21"
-    RenderBR {BR} at (17,421) size 0x19
+    LayoutBR {BR} at (17,421) size 0x19
     RenderText {#text} at (1,441) size 16x19
       text run at (1,441) width 16: "22"
-    RenderBR {BR} at (17,441) size 0x19
+    LayoutBR {BR} at (17,441) size 0x19
     RenderText {#text} at (1,461) size 16x19
       text run at (1,461) width 16: "23"
-    RenderBR {BR} at (17,461) size 0x19
+    LayoutBR {BR} at (17,461) size 0x19
     RenderText {#text} at (1,481) size 16x19
       text run at (1,481) width 16: "24"
-    RenderBR {BR} at (17,481) size 0x19
+    LayoutBR {BR} at (17,481) size 0x19
     RenderText {#text} at (1,501) size 16x19
       text run at (1,501) width 16: "25"
-    RenderBR {BR} at (17,501) size 0x19
+    LayoutBR {BR} at (17,501) size 0x19
     RenderText {#text} at (1,521) size 16x19
       text run at (1,521) width 16: "26"
-    RenderBR {BR} at (17,521) size 0x19
+    LayoutBR {BR} at (17,521) size 0x19
     RenderText {#text} at (1,541) size 16x19
       text run at (1,541) width 16: "27"
-    RenderBR {BR} at (17,541) size 0x19
+    LayoutBR {BR} at (17,541) size 0x19
     RenderText {#text} at (1,561) size 16x19
       text run at (1,561) width 16: "28"
-    RenderBR {BR} at (17,561) size 0x19
+    LayoutBR {BR} at (17,561) size 0x19
     RenderText {#text} at (1,581) size 16x19
       text run at (1,581) width 16: "29"
-    RenderBR {BR} at (17,581) size 0x19
+    LayoutBR {BR} at (17,581) size 0x19
     RenderText {#text} at (1,601) size 16x19
       text run at (1,601) width 16: "30"
-    RenderBR {BR} at (17,601) size 0x19
+    LayoutBR {BR} at (17,601) size 0x19
 hidden layer at (8,28) size 8x20
   RenderBlock (positioned) {SPAN} at (8,28) size 8x20
     RenderText {#text} at (0,0) size 8x19
       text run at (0,0) width 8: "0"
 caret: position 1 of child 36 {#text} of child 5 {DIV} of body