atof: added 'E' as valid token for exponent

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/3827042

src/pkg/strconv/atof.go

@@ -107,7 +107,7 @@ func stringToDecimal(s string) (neg bool, d *decimal, trunc bool, ok bool) {
 	// just be sure to move the decimal point by
 	// a lot (say, 100000).  it doesn't matter if it's
 	// not the exact number.
-	if i < len(s) && s[i] == 'e' {
+	if i < len(s) && (s[i] == 'e' || s[i] == 'E') {
 		i++
 		if i >= len(s) {
 			return

src/pkg/strconv/atof_test.go

@@ -24,6 +24,7 @@ var atoftests = []atofTest{
 	{"1x", "0", os.EINVAL},
 	{"1.1.", "0", os.EINVAL},
 	{"1e23", "1e+23", nil},
+	{"1E23", "1e+23", nil},
 	{"100000000000000000000000", "1e+23", nil},
 	{"1e-100", "1e-100", nil},
 	{"123456700", "1.234567e+08", nil},