[FIX] web: WidgetDomain: don't crash on false domain

Before this rev., when the value of a field with widget='domain'
was false, the search_count RPC made to display the number of
records matching the domain crashed, and the widget displayed that
the domain was invalid. This rev. adds a fallback on [] when the
domain is false.

addons/web/static/src/js/views/basic/basic_model.js

@@ -2043,7 +2043,7 @@ var BasicModel = AbstractModel.extend({
         if (record.data.hasOwnProperty(domainModel)) {
             domainModel = record._changes && record._changes[domainModel] || record.data[domainModel];
         }
-        var domainValue = record._changes && record._changes[fieldName] || record.data[fieldName];
+        var domainValue = record._changes && record._changes[fieldName] || record.data[fieldName] || [];
 
         // avoid rpc if not necessary
         var hasChanged = this._saveSpecialDataCache(record, fieldName, {

addons/web/static/tests/fields/basic_fields_tests.js

@@ -3757,6 +3757,44 @@ QUnit.module('basic_fields', {
             "field selector popover should contain 'Color index' field");
         form.destroy();
     });
+
+    QUnit.test('domain field: handle false domain as []', function (assert) {
+        assert.expect(2);
+
+        this.data.partner.records[0].foo = false;
+        this.data.partner.fields.bar.type = "char";
+        this.data.partner.records[0].bar = "product";
+
+        var form = createView({
+            View: FormView,
+            model: 'partner',
+            data: this.data,
+            arch:
+                '<form>' +
+                    '<sheet>' +
+                        '<group>' +
+                            '<field name="bar"/>' +
+                            '<field name="foo" widget="domain" options="{\'model\': \'bar\'}"/>' +
+                        '</group>' +
+                    '</sheet>' +
+                '</form>',
+            mockRPC: function (route, args) {
+                if (args.method === 'search_count') {
+                    assert.deepEqual(args.args[0], [], "should send a valid domain");
+                }
+                return this._super.apply(this, arguments);
+            },
+            res_id: 1,
+            viewOptions: {
+                mode: 'edit',
+            },
+        });
+
+        var $warning = form.$('.o_field_widget[name=foo] .text-warning');
+        assert.strictEqual($warning.length, 0, "should not display that the domain is invalid");
+
+        form.destroy();
+    });
 });
 });
 });