[dart:io] Namespaces for file IO

runtime/bin/security_context_linux.cc

Index: runtime/bin/security_context_linux.cc
diff --git a/runtime/bin/security_context_linux.cc b/runtime/bin/security_context_linux.cc
index 0fd773771c83068a4db4ab596b5a921fa1e14d96..9c31dc0afcb4549ef59f6bf9d806208654351f8b 100644
--- a/runtime/bin/security_context_linux.cc
+++ b/runtime/bin/security_context_linux.cc
@@ -51,12 +51,12 @@ void SSLCertContext::TrustBuiltinRoots() {
   // https://www.happyassassin.net/2015/01/12/a-note-about-ssltls-trusted-certificate-stores-and-platforms/
   const char* bundle = "/etc/pki/tls/certs/ca-bundle.crt";
   const char* cachedir = "/etc/ssl/certs";
-  if (File::Exists(bundle)) {
+  if (File::Exists(NULL, bundle)) {
     LoadRootCertFile(bundle);
     return;
   }
 
-  if (Directory::Exists(cachedir) == Directory::EXISTS) {
+  if (Directory::Exists(NULL, cachedir) == Directory::EXISTS) {
     LoadRootCertCache(cachedir);
     return;
   }