Cleanup in //runtime/bin

runtime/bin/builtin.cc

 // 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.
 
 #include <stdio.h>
 
 #include "include/dart_api.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
@@ skipping 20 matching lines @@
     Dart_Handle patch_src = DartUtils::ReadStringFromFile(patch_files[j + 1]);
     if (!Dart_IsString(patch_src)) {
       // In case reading the file caused an error, use the sources directly.
       const char* source = patch_files[j + 2];
       patch_src = Dart_NewStringFromUTF8(
           reinterpret_cast<const uint8_t*>(source), strlen(source));
     }
 
     // Prepend the patch library URI to form a unique script URI for the patch.
     intptr_t len = snprintf(NULL, 0, "%s/%s", patch_uri, patch_files[j]);
-    char* patch_filename = reinterpret_cast<char*>(malloc(len + 1));
+    char* patch_filename = DartUtils::ScopedCString(len + 1);
     snprintf(patch_filename, len + 1, "%s/%s", patch_uri, patch_files[j]);
     Dart_Handle patch_file_uri = DartUtils::NewString(patch_filename);
-    free(patch_filename);
 
     DART_CHECK_VALID(Dart_LibraryLoadPatch(library, patch_file_uri, patch_src));
   }
 }
 
 
 Dart_Handle Builtin::Source(BuiltinLibraryId id) {
   ASSERT((sizeof(builtin_libraries_) / sizeof(builtin_lib_props)) ==
          kInvalidLibrary);
   ASSERT(id >= kBuiltinLibrary && id < kInvalidLibrary);
@@ skipping 66 matching lines @@
   Dart_Handle url = DartUtils::NewString(builtin_libraries_[id].url_);
   Dart_Handle library = Dart_LookupLibrary(url);
   if (Dart_IsError(library)) {
     library = LoadLibrary(url, id);
   }
   return library;
 }
 
 }  // namespace bin
 }  // namespace dart