gojs: implements umask (#1230)

This implements host-side umask for gojs, which allows
`os.TestMkdirStickyUmask` to pass.

Signed-off-by: Adrian Cole <adrian@tetrate.io>

internal/gojs/state.go

@@ -24,6 +24,7 @@ func NewState(ctx context.Context) *State {
 		values:                 values.NewValues(),
 		valueGlobal:            newJsGlobal(getRoundTripper(ctx)),
 		cwd:                    getWorkdir(ctx),
+		umask:                  0o0022,
 		_nextCallbackTimeoutID: 1,
 		_scheduledTimeouts:     map[uint32]chan bool{},
 	}
@@ -190,6 +191,8 @@ type State struct {
 
 	// cwd is initially "/"
 	cwd string
+	// umask is initially 0022
+	umask uint32
 }
 
 // Get implements the same method as documented on goos.GetFunction
@@ -226,6 +229,7 @@ func (s *State) close() {
 	s._lastEvent = nil
 	s._nextCallbackTimeoutID = 1
 	s.cwd = "/"
+	s.umask = 0o0022
 }
 
 func toInt64(arg interface{}) int64 {