Fix JSHint errors in theme-install.js.

props kovshenin.
fixes #26045.


git-svn-id: https://develop.svn.wordpress.org/trunk@26210 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fourteen: use HTML entity for arrow in Help text string, props dd32. See #25837.

git-svn-id: https://develop.svn.wordpress.org/trunk@26211 602fd350-edb4-49c9-b593-d223f7449a82