Just like os.environ, the Environment class should allow for a default argument in the `get` function call.
<rdar://problem/100482618>
Pull request: https://github.com/WebKit/WebKit/pull/4777
Committed 254954@main (cde78ac0d823): <https://commits.webkit.org/254954@main> Reviewed commits have been landed. Closing PR #4777 and removing active labels.
Committed 252432.493@safari-7614-branch (5f93f28b7e67): <https://commits.webkit.org/252432.493@safari-7614-branch> Reviewed commits have been landed. Closing PR #86 and removing active labels.