Fixes some memory leaks in //runtime/bin

runtime/bin/dartutils.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 BIN_DARTUTILS_H_
 #define BIN_DARTUTILS_H_
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 
@@ skipping 147 matching lines @@
                                         const char* message,
                                         Dart_Handle os_error);
 
   // Create a new Dart String object from a C String.
   static Dart_Handle NewString(const char* str) {
     ASSERT(str != NULL);
     return Dart_NewStringFromUTF8(reinterpret_cast<const uint8_t*>(str),
                                   strlen(str));
   }
 
+  // Allocate length bytes for a C string with Dart_ScopeAllocate.
+  static char* ScopedCString(intptr_t length) {
+    char* result = NULL;
+    result = reinterpret_cast<char*>(
+        Dart_ScopeAllocate(length * sizeof(*result)));
+    return result;
+  }
+
+  // Copy str into a buffer allocated with Dart_ScopeAllocate.
+  static char* ScopedCopyCString(const char* str) {
+    size_t str_len = strlen(str);
+    char* result = ScopedCString(str_len + 1);
+    memmove(result, str, str_len);
+    result[str_len] = '\0';
+    return result;
+  }
+
   // Create a new Dart InternalError object with the provided message.
   static Dart_Handle NewError(const char* format, ...);
   static Dart_Handle NewInternalError(const char* message);
 
   static Dart_Handle BuiltinLib() {
     IsolateData* isolate_data =
         reinterpret_cast<IsolateData*>(Dart_CurrentIsolateData());
     return isolate_data->builtin_lib();
   }
 
@@ skipping 406 matching lines @@
 
   ~ScopedBlockingCall() {
     Dart_ThreadEnableProfiling();
   }
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_DARTUTILS_H_