Fix bots

runtime/vm/dev_fs.cc

Index: runtime/vm/dev_fs.cc
diff --git a/runtime/vm/dev_fs.cc b/runtime/vm/dev_fs.cc
index 6a9a76c62c381f7d8f18320de531f4b710f8a52e..0ad6b0d3040fa988778f5fa64e64b08a1be3c93a 100644
--- a/runtime/vm/dev_fs.cc
+++ b/runtime/vm/dev_fs.cc
@@ -108,7 +108,8 @@ class FileSystem {
     for (iter = files_.begin(); iter != files_.end(); iter++) {
       JSONObject file_info(&jsarr);
       file_info.AddProperty("name", iter->first.c_str());
-      file_info.AddProperty("size", static_cast<int64_t>(iter->second->size()));
+      file_info.AddProperty64("size",
+                              static_cast<int64_t>(iter->second->size()));
     }
   }