Do not externalize Dart strings as C strings for "print()".

runtime/include/dart_api.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 INCLUDE_DART_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
  *
  * Dart is a class-based programming language for creating structured
@@ skipping 1238 matching lines @@
  * \param str A string.
  * \param utf8 Returns the String represented as a utf8 encoded C
  *   string. This C string is scope allocated and is only valid until
  *   the next call to Dart_ExitScope.
  *
  * \return A valid handle if no error occurs during the operation.
  */
 DART_EXPORT Dart_Handle Dart_StringToCString(Dart_Handle str,
                                              const char** utf8);
 
+/**
+ * Gets a UTF-8 encoded representation of a String.
+ *
+ * \param str A string.
+ * \param bytes Returns the String represented as an array of UTF-8
+ *   code units. This array is scope allocated and is only valid until
+ *   the next call to Dart_ExitScope.
+ * \param length Returns the length of the code units array, in bytes.
+ *
+ * \return A valid handle if no error occurs during the operation.
+ */
+DART_EXPORT Dart_Handle Dart_StringToBytes(Dart_Handle str,
+                                           const uint8_t** bytes,
+                                           intptr_t* length);
+
 // --- Lists ---
 
 /**
  * Is this object a List?
  */
 DART_EXPORT bool Dart_IsList(Dart_Handle object);
 
 /**
  * Returns a List of the desired length.
  *
@@ skipping 723 matching lines @@
 
 // --- Profiling support ----
 
 // External pprof support for gathering and dumping symbolic
 // information that can be used for better profile reports for
 // dynamically generated code.
 DART_EXPORT void Dart_InitPprofSupport();
 DART_EXPORT void Dart_GetPprofSymbolInfo(void** buffer, int* buffer_size);
 
 #endif  // INCLUDE_DART_API_H_