Fix required to migrate number field on d7 webform with select options.

webform_migrate_number_field.diff

diff --git a/src/Plugin/migrate/source/d7/D7Webform.php b/src/Plugin/migrate/source/d7/D7Webform.php
index cf58dba..00ad5c4 100644
--- a/src/Plugin/migrate/source/d7/D7Webform.php
+++ b/src/Plugin/migrate/source/d7/D7Webform.php
@@ -442,7 +442,7 @@ class D7Webform extends DrupalSqlBase implements ImportAwareInterface, RollbackA
             $max = $extra['max'];
             $step = !empty($extra['step']) ? $extra['step'] : 1;
             for ($value = $min; $value <= $max; $value += $step) {
-              $new_element[$value] = $value;
+              $new_element['#options'][$value] = $value;
             }
           }
           foreach (['min', 'max', 'step'] as $property) {