time: handle negative offsets on js/wasm

Fixes #28649

Change-Id: I9f6807ee3c3007f670dd509780805c7b255a2bda
Reviewed-on: https://go-review.googlesource.com/c/148338
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/time/zoneinfo_js.go b/src/time/zoneinfo_js.go
index d640c831bfe828769e770e4d53253b4aa625d098..2d76a571f2178fec234e839a2802f205539846a0 100644 (file)
--- a/src/time/zoneinfo_js.go
+++ b/src/time/zoneinfo_js.go
@@ -33,6 +33,7 @@ func initLocal() {
        z.name = "UTC"
        if offset < 0 {
                z.name += "-"
+               offset *= -1
        } else {
                z.name += "+"
        }
@@ -44,8 +45,8 @@ func initLocal() {
        localLoc.zone = []zone{z}
 }
 
-// itoa is just the fast path implementation copied from strconv.Itoa.
-// No timezone hour can exceed 100, so the fast path will always satisfy.
+// itoa is like strconv.Itoa but only works for values of i in range [0,99].
+// It panics if i is out of range.
 func itoa(i int) string {
        if i < 10 {
                return digits[i : i+1]