Remove Sky tests that we don't intend to port to the new world

sky/tests/lowlevel/filters-expected.sky

Index: sky/tests/lowlevel/filters-expected.sky
diff --git a/sky/tests/lowlevel/filters-expected.sky b/sky/tests/lowlevel/filters-expected.sky
deleted file mode 100644
index 34757d00717860359561aa2e3c92d11d9623128f..0000000000000000000000000000000000000000
--- a/sky/tests/lowlevel/filters-expected.sky
+++ /dev/null
@@ -1,18 +0,0 @@
-<foo>
-<import src="../resources/run-after-display.sky" />
-
-<img src="http://storage.googleapis.com/mojo/sky-pngs/9a7b59f74e2bbcd0d0ceee17ead05b0da64a2af7" />
-
-<script>
-import "dart:sky";
-import "dart:sky.internals" as internals;
-
-void main() {
-  window.addEventListener('load', (_) {
-    runAfterDisplay(() {
-      internals.notifyTestComplete("");
-    });
-  });
-}
-</script>
-</foo>