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://golang.org/cl/91880044

src/pkg/net/http/fs.go

@@ -212,12 +212,6 @@ func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time,
 			code = StatusPartialContent
 			w.Header().Set("Content-Range", ra.contentRange(size))
 		case len(ranges) > 1:
-			for _, ra := range ranges {
-				if ra.start > size {
-					Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
-					return
-				}
-			}
 			sendSize = rangesMIMESize(ranges, ctype, size)
 			code = StatusPartialContent