net/http: remove a duplicated check
net/http: remove a duplicated check

The previous call to parseRange already checks whether
all the ranges start before the end of file.

LGTM=robert.hencke, bradfitz
R=golang-codereviews, robert.hencke, gobot, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/91880044

Committer: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go,tv42/old-go