This allows HTML pages to specify arbitrary data in a header: <!--{ "Title": "The page title", ... }--> replacing the old style comments: <!-- title The page title --> R=gri, rsc, r, bradfitz, dsymonds CC=golang-dev https://golang.org/cl/5532093
R=r, rsc, gri CC=golang-dev, iant, ken2, lvd, nigeltao_golang, stephenm https://golang.org/cl/2182042