- Add missing explicit in constructor.

runtime/vm/json_stream.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_JSON_STREAM_H_
 #define VM_JSON_STREAM_H_
 
 #include "platform/json.h"
 #include "vm/allocation.h"
 
@@ skipping 106 matching lines @@
 
 
 class JSONArray : public ValueObject {
  public:
   explicit JSONArray(JSONStream* stream) : stream_(stream) {
     stream_->OpenArray();
   }
   JSONArray(const JSONObject& obj, const char* name) : stream_(obj.stream_) {
     stream_->OpenArray(name);
   }
-  JSONArray(const JSONArray& arr) : stream_(arr.stream_) {
+  explicit JSONArray(const JSONArray& arr) : stream_(arr.stream_) {
     stream_->OpenArray();
   }
   ~JSONArray() {
     stream_->CloseArray();
   }
 
   void AddValue(bool b) const { stream_->PrintValueBool(b); }
   void AddValue(intptr_t i) const { stream_->PrintValue(i); }
   void AddValue(double d) const { stream_->PrintValue(d); }
   void AddValue(const char* s) const { stream_->PrintValue(s); }
   void AddValue(const Object& obj, bool ref = true) const {
     stream_->PrintValue(obj, ref);
   }
   void AddValueF(const char* format, ...) const PRINTF_ATTRIBUTE(2, 3);
 
  private:
   JSONStream* stream_;
 
   friend class JSONObject;
 };
 
 }  // namespace dart
 
 #endif  // VM_JSON_STREAM_H_