Merge pull request #1829 from 9rnsr/fix9773

Issue 9773 - ref parameter with default string literal should not compile
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd
Merge branch 'master' of github.com:D-Programming-Language/dmd