Fix presubmit style warning for gdb-jit.cc

src/gdb-jit.cc

 // Copyright 2010 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 611 matching lines @@
 
 
   ZoneList<MachOSection*> sections_;
 };
 #endif  // defined(__MACH_O)
 
 
 #if defined(__ELF)
 class ELF BASE_EMBEDDED {
  public:
-  ELF(Zone* zone) : sections_(6, zone) {
+  explicit ELF(Zone* zone) : sections_(6, zone) {
     sections_.Add(new(zone) ELFSection("", ELFSection::TYPE_NULL, 0), zone);
     sections_.Add(new(zone) ELFStringTable(".shstrtab"), zone);
   }
 
   void Write(Writer* w) {
     WriteHeader(w);
     WriteSectionTable(w);
     WriteSections(w);
   }
 
@@ skipping 1526 matching lines @@
   ScopedLock lock(mutex.Pointer());
   ASSERT(!IsLineInfoTagged(line_info));
   HashMap::Entry* e = GetEntries()->Lookup(code, HashForCodeObject(code), true);
   ASSERT(e->value == NULL);
   e->value = TagLineInfo(line_info);
 }
 
 
 } }  // namespace v8::internal
 #endif