misc/pprof: fix html5 doctype declaration
misc/pprof: fix html5 doctype declaration

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/10099045

gnanderson/go,pombredanne/go-deleteme,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,gnanderson/go,gnanderson/go,tv42/old-go,tv42/old-go,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,pombredanne/go-deleteme,pombredanne/go-deleteme,gnanderson/go,gnanderson/go,tv42/old-go,pombredanne/go-deleteme,apparentlymart/golang,apparentlymart/golang,gnanderson/go,pombredanne/go-deleteme,gnanderson/go,tv42/old-go,tv42/old-go,apparentlymart/golang,tv42/old-go