func BenchmarkParseNumber(b *testing.B) {

Hi Dave
I think a small change should be done for this func()
To see an issue quickly just run this line
go test -bench=.Parse.

`

panic: runtime error: index out of range [0] with length 0

goroutine 290 [running]:
github.com/pkg/json.BenchmarkParseNumber.func1(0xc000194240)
C:/Users/VE/go/dev/src/davecheney/pkg/json-master/scanner_test.go:157 +0x51
testing.(*B).runN(0xc000194240, 0x1)
C:/Go/src/testing/benchmark.go:191 +0xf2
testing.(*B).run1.func1(0xc000194240)
C:/Go/src/testing/benchmark.go:231 +0x5e
created by testing.(*B).run1
C:/Go/src/testing/benchmark.go:224 +0x85
exit status 2
`

// --------------------------------------------------------------------------------------------------------------

`

		for i := 0; i < b.N; i++ {
			r.Seek(0, 0)
			scanner := &Scanner{
				br: byteReader{
					data: buf[:0],
					r:    r,
				},
			}
			scanner.Next()                                       // add scanner.Next() here to escape panic
			n := scanner.parseNumber(scanner.br.window(0)[0])    // panic was here

`