Add attributions so printf like functions can have their arguments checked.

runtime/vm/object.h

 // Copyright (c) 2012, 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_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 3522 matching lines @@
 
   static RawString* Transform(int32_t (*mapping)(int32_t ch),
                               const String& str,
                               Heap::Space space = Heap::kNew);
 
   static RawString* ToUpperCase(const String& str,
                                 Heap::Space space = Heap::kNew);
   static RawString* ToLowerCase(const String& str,
                                 Heap::Space space = Heap::kNew);
 
-  static RawString* NewFormatted(const char* format, ...);
+  static RawString* NewFormatted(const char* format, ...)
+      PRINTF_ATTRIBUTE(1, 2);
 
  protected:
   bool HasHash() const {
     ASSERT(Smi::New(0) == NULL);
     return (raw_ptr()->hash_ != NULL);
   }
 
   void SetLength(intptr_t value) const {
     // This is only safe because we create a new Smi, which does not cause
     // heap allocation.
@@ skipping 2008 matching lines @@
     if (this->CharAt(i) != str.CharAt(begin_index + i)) {
       return false;
     }
   }
   return true;
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_