Return map instead of pointer value

As kisielk just [told me](709e005f84 (commitcomment-3636470),) maps can be nil

context.go

@@ -49,12 +49,12 @@ func GetOk(r *http.Request, key interface{}) (interface{}, bool) {
 }
 
 // GetAll returns all stored values for the request as a map. Nil is returned for invalid requests.
-func GetAll(r *http.Request) *map[interface{}]interface{} {
+func GetAll(r *http.Request) map[interface{}]interface{} {
 	mutex.Lock()
 	defer mutex.Unlock()
 
 	if context, ok := data[r]; ok {
-		return &context
+		return context
 	}
 	return nil
 }

context_test.go

@@ -54,7 +54,7 @@ func TestContext(t *testing.T) {
 
 	// GetAll()
 	values := GetAll(r)
-	assertEqual(len(*values), 3)
+	assertEqual(len(values), 3)
 
 	// GetAll() for empty request
 	values = GetAll(emptyR)