Upgrade V8 to 5.1.281.57  DO NOT MERGE

FPIIM-449

Change-Id: Id981b686b4d587ac31697662eb98bb34be42ad90
(cherry picked from commit 3b9bc31999c9787eb726ecdbfd5796bfdec32a18)
diff --git a/src/arm/assembler-arm.h b/src/arm/assembler-arm.h
index d381653..08ad64c 100644
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -1390,7 +1390,9 @@
   // Emits the address of the code stub's first instruction.
   void emit_code_stub_address(Code* stub);
 
-  PositionsRecorder* positions_recorder() { return &positions_recorder_; }
+  AssemblerPositionsRecorder* positions_recorder() {
+    return &positions_recorder_;
+  }
 
   // Read/patch instructions
   Instr instr_at(int pos) { return *reinterpret_cast<Instr*>(buffer_ + pos); }
@@ -1637,8 +1639,8 @@
   friend class RelocInfo;
   friend class CodePatcher;
   friend class BlockConstPoolScope;
-  PositionsRecorder positions_recorder_;
-  friend class PositionsRecorder;
+  AssemblerPositionsRecorder positions_recorder_;
+  friend class AssemblerPositionsRecorder;
   friend class EnsureSpace;
 };