Revert "Make line breaks in <blockquote> behave like <div> (bug 6200)."  See bug 52763

This reverts commit b9d0e5e4e763aa58647f88739ed0e5682685d064.

Change-Id: I9451f7d11fe01085e4289b21b2e905751bdbf800
Merge "Revert "Make line breaks in <blockquote> behave like <div> (bug 6200)."  See bug 52763"