Add convinience script for uploading changes to performance tracking.

Change-Id: Id49e298eed5128184e854c6e9e828b63697792c3
diff --git a/third_party/dart-sdk.tar.gz.sha1 b/third_party/dart-sdk.tar.gz.sha1
new file mode 100644
index 0000000..f8b4a60
--- /dev/null
+++ b/third_party/dart-sdk.tar.gz.sha1
@@ -0,0 +1 @@
+0f15c6a81827ce4979b6fcf6183ef35df335d9dc
\ No newline at end of file