make sure subwidgets have proper parents

web/static/src/ts/core/qweb_vdom.ts

@@ -682,7 +682,7 @@ const widgetDirective: Directive = {
     let props = node.getAttribute("t-props");
     let widgetID = ctx.generateID();
     ctx.addLine(
-      `let _${widgetID} = new context.widgets['${value}'](context, ${props})`
+      `let _${widgetID} = new context.widgets['${value}'](owner, ${props})`
     );
     ctx.addLine(
       `let def${defID} = _${widgetID}._start().then(() => _${widgetID}._render()).then(vnode=>{Object.assign(_${dummyID}, vnode);_${dummyID}.key="${dummyID}";_${dummyID}.data.hook = {create(_,vn){_${widgetID}._mount(vn)}}})`

web/static/tests/widget.test.ts

@@ -265,6 +265,7 @@ describe("composition", () => {
     const widget = new WidgetA(env);
     await widget.mount(fixture);
     expect(fixture.innerHTML).toBe("<div>Hello<div>world</div></div>");
+    expect(widget._.children[0]._.parent).toBe(widget);
   });
 
   test("t-refs on widget are widgets", async () => {