Fix presubmit error.

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include "src/allocation.h"
 #include "src/assert-scope.h"
 #include "src/builtins.h"
@@ skipping 7523 matching lines @@
 #error Unknown byte ordering
 #endif
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(SharedFunctionInfo);
 };
 
 
 // Printing support.
 struct SourceCodeOf {
-  SourceCodeOf(SharedFunctionInfo* v, int max = -1)
+  explicit SourceCodeOf(SharedFunctionInfo* v, int max = -1)
       : value(v), max_length(max) {}
   const SharedFunctionInfo* value;
   int max_length;
 };
 
 
 OStream& operator<<(OStream& os, const SourceCodeOf& v);
 
 
 class JSGeneratorObject: public JSObject {
@@ skipping 2183 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ConsStringNullOp);
 };
 
 
 // This maintains an off-stack representation of the stack frames required
 // to traverse a ConsString, allowing an entirely iterative and restartable
 // traversal of the entire string
 class ConsStringIteratorOp {
  public:
   inline ConsStringIteratorOp() {}
-  inline ConsStringIteratorOp(ConsString* cons_string, int offset = 0) {
+  inline explicit ConsStringIteratorOp(ConsString* cons_string,
+                                       int offset = 0) {
     Reset(cons_string, offset);
   }
   inline void Reset(ConsString* cons_string, int offset = 0) {
     depth_ = 0;
     // Next will always return NULL.
     if (cons_string == NULL) return;
     Initialize(cons_string, offset);
   }
   // Returns NULL when complete.
   inline String* Next(int* offset_out) {
@@ skipping 1505 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_