[test] Process to locally develop and upstream test262 tests

test/test262/prune-local-tests.sh

+# Copyright 2016 the V8 project authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# usage: test/test262/prune-local-tests.sh
+# This script removes redundant tests present in the local-tests directory
+# when they are identical to upstreamed tests. It should be run as part of
+# the test262 roll process.
+
+find -f test/test262/local-tests | while read localpath; do
+  datapath=${localpath/local-tests/data}
+  if diff $localpath $datapath >/dev/null ; then
+    git rm $localpath || exit 1
+  fi
+done