Fix A64 build: unwrap HSourcePosition into int before recording.

src/a64/lithium-a64.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2809 matching lines @@
  public:
   LChunkBuilder(CompilationInfo* info, HGraph* graph, LAllocator* allocator)
       : LChunkBuilderBase(graph->zone()),
         chunk_(NULL),
         info_(info),
         graph_(graph),
         status_(UNUSED),
         current_instruction_(NULL),
         current_block_(NULL),
         allocator_(allocator),
-        position_(RelocInfo::kNoPosition),
         instruction_pending_deoptimization_environment_(NULL),
         pending_deoptimization_ast_id_(BailoutId::None()) { }
 
   // Build the sequence for the graph.
   LPlatformChunk* Build();
 
   LInstruction* CheckElideControlInstruction(HControlInstruction* instr);
 
   // Declare methods that deal with the individual node types.
 #define DECLARE_DO(type) LInstruction* Do##type(H##type* node);
@@ skipping 108 matching lines @@
   LInstruction* DoArithmeticT(Token::Value op,
                               HBinaryOperation* instr);
 
   LPlatformChunk* chunk_;
   CompilationInfo* info_;
   HGraph* const graph_;
   Status status_;
   HInstruction* current_instruction_;
   HBasicBlock* current_block_;
   LAllocator* allocator_;
-  int position_;
   LInstruction* instruction_pending_deoptimization_environment_;
   BailoutId pending_deoptimization_ast_id_;
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_A64_LITHIUM_A64_H_