Fix presubmit errors introduced by r5768.

src/assembler.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 611 matching lines @@
   PositionRecordingType current_position_recording_type_;
   int written_position_;
 
   int current_statement_position_;
   int written_statement_position_;
 };
 
 
 class PreserveStatementPositionScope BASE_EMBEDDED {
  public:
-  PreserveStatementPositionScope(PositionsRecorder* positions_recorder)
+  explicit PreserveStatementPositionScope(PositionsRecorder* positions_recorder)
       : positions_recorder_(positions_recorder),
         statement_position_(positions_recorder->current_statement_position()) {}
 
   ~PreserveStatementPositionScope() {
     if (statement_position_ != RelocInfo::kNoPosition) {
       positions_recorder_->RecordStatementPosition(statement_position_);
     }
   }
 
  private:
@@ skipping 35 matching lines @@
   unsigned int num_bits_set;
   for (num_bits_set = 0; x; x >>= 1) {
     num_bits_set += x & 1;
   }
   return num_bits_set;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_