Update .gitignore wrt promise test files.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/259593002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@20942 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

.gitignore

@@ -46,6 +46,9 @@ shell_g
 /test/mozilla/CHECKED_OUT_VERSION
 /test/mozilla/data
 /test/mozilla/downloaded_*
+/test/promises-aplus/promises-tests
+/test/promises-aplus/promises-tests.tar.gz
+/test/promises-aplus/sinon
 /test/test262/data
 /test/test262/tc39-test262-*
 /third_party