Check that the C string passed to Dart_NewString is valid UTF-8.

runtime/vm/unicode.h

 // Copyright (c) 2011, 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_UNICODE_H_
 #define VM_UNICODE_H_
 
 #include "vm/allocation.h"
 #include "vm/globals.h"
 
 namespace dart {
 
 class String;
 
 class Utf8 : AllStatic {
  public:
   static const intptr_t kMaxOneByteChar   = 0x7F;
   static const intptr_t kMaxTwoByteChar   = 0x7FF;
   static const intptr_t kMaxThreeByteChar = 0xFFFF;
   static const intptr_t kMaxFourByteChar  = 0x10FFFF;
 
   static intptr_t CodePointCount(const char* str, intptr_t* width);
 
+  static bool IsValid(const char* src);
+
   static intptr_t Length(int32_t ch);
   static intptr_t Length(const String& str);
 
   static intptr_t Encode(int32_t ch, char* dst);
   static intptr_t Encode(const String& src, char* dst, intptr_t len);
 
   static intptr_t Decode(const char*, int32_t* ch);
   static bool Decode(const char* src, uint8_t* dst, intptr_t len);
   static bool Decode(const char* src, uint16_t* dst, intptr_t len);
   static bool Decode(const char* src, uint32_t* dst, intptr_t len);
@@ skipping 59 matching lines @@
   // Data for small code points with one mapping
   static const int16_t stage2_[];
 
   // Data for large code points or code points with both mappings.
   static const int32_t stage2_exception_[][2];
 };
 
 }  // namespace dart
 
 #endif  // VM_UNICODE_H_