Implement File.directory() and File.directorySync() to get

runtime/bin/file_linux.cc

Index: runtime/bin/file_linux.cc
diff --git a/runtime/bin/file_linux.cc b/runtime/bin/file_linux.cc
index e28c322982f320141657a44cd30a954c1f74fc0b..825bdea47fabc5f68c68e0db6cfec9dbefcec901 100644
--- a/runtime/bin/file_linux.cc
+++ b/runtime/bin/file_linux.cc
@@ -177,6 +177,15 @@ char* File::GetCanonicalPath(const char* pathname) {
 }
 
 
+char* File::GetContainingDirectory(char* pathname) {
+  char* path = NULL;
+  do {
+    path = dirname(pathname);
+  } while (path == NULL && errno == EINTR);
+  return GetCanonicalPath(path);
+}
+
+
 const char* File::PathSeparator() {
   return "/";
 }