[FIX] qweb, t-call: t-call nested in t-slot

Have a t-call within a t-set-slot of a component.
The called template has a t-component directive.

It should be like:

```xml
<t t-name="Zero">
  <Slotted>
    <t t-call="someTemplate" />
  </Slotted>
</t>

<t t-name="someTemplate">
  <SomeComponent />
</t>
```

Before this commit, the parent of SomeComponent was the Zero component

After this commit, the parent of SomeComponent is the Slotted Component as it should be

closes #862

tests/component/__snapshots__/component.test.ts.snap

@@ -1573,6 +1573,7 @@ exports[`t-call handlers are properly bound through a t-call 1`] = `
 ) {
     // Template name: \\"sub\\"
     let utils = this.constructor.utils;
+    let parent = extra.parent;
     let h = this.h;
     let c2 = extra.parentNode;
     let key0 = extra.key || \\"\\";
@@ -1591,6 +1592,7 @@ exports[`t-call handlers with arguments are properly bound through a t-call 1`]
 ) {
     // Template name: \\"sub\\"
     let utils = this.constructor.utils;
+    let parent = extra.parent;
     let scope = Object.create(context);
     let h = this.h;
     let c2 = extra.parentNode;

tests/component/__snapshots__/slots.test.ts.snap

@@ -68,6 +68,7 @@ exports[`t-slot directive can define and call slots 3`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_header_template\\"
+    let parent = extra.parent;
     let h = this.h;
     let c4 = extra.parentNode;
     let c5 = [], p5 = {key:5};
@@ -81,6 +82,7 @@ exports[`t-slot directive can define and call slots 4`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_footer_template\\"
+    let parent = extra.parent;
     let h = this.h;
     let c6 = extra.parentNode;
     let c7 = [], p7 = {key:7};
@@ -158,6 +160,7 @@ exports[`t-slot directive can define and call slots using old t-set keyword 3`]
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_header_template\\"
+    let parent = extra.parent;
     let h = this.h;
     let c4 = extra.parentNode;
     let c5 = [], p5 = {key:5};
@@ -171,6 +174,7 @@ exports[`t-slot directive can define and call slots using old t-set keyword 4`]
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_footer_template\\"
+    let parent = extra.parent;
     let h = this.h;
     let c6 = extra.parentNode;
     let c7 = [], p7 = {key:7};
@@ -184,6 +188,7 @@ exports[`t-slot directive content is the default slot 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let h = this.h;
     let c4 = extra.parentNode;
     let c5 = [], p5 = {key:5};
@@ -214,6 +219,7 @@ exports[`t-slot directive default slot work with text nodes 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let h = this.h;
     let c4 = extra.parentNode;
     c4.push({text: \`sts rocks\`});
@@ -243,6 +249,7 @@ exports[`t-slot directive multiple roots are allowed in a default slot 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let h = this.h;
     let c4 = extra.parentNode;
     let c5 = [], p5 = {key:5};
@@ -260,6 +267,7 @@ exports[`t-slot directive multiple roots are allowed in a named slot 1`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_content_template\\"
+    let parent = extra.parent;
     let h = this.h;
     let c4 = extra.parentNode;
     let c5 = [], p5 = {key:5};
@@ -295,6 +303,7 @@ exports[`t-slot directive refs are properly bound in slots 1`] = `
 ) {
     // Template name: \\"slot_footer_template\\"
     let utils = this.constructor.utils;
+    let parent = extra.parent;
     context.__owl__.refs = context.__owl__.refs || {};
     let h = this.h;
     let c8 = extra.parentNode;
@@ -321,6 +330,7 @@ exports[`t-slot directive slots are rendered with proper context 1`] = `
 ) {
     // Template name: \\"slot_footer_template\\"
     let utils = this.constructor.utils;
+    let parent = extra.parent;
     let h = this.h;
     let c8 = extra.parentNode;
     let c9 = [], p9 = {key:9,on:{}};
@@ -418,6 +428,7 @@ exports[`t-slot directive slots are rendered with proper context, part 2 3`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let scope = Object.create(context);
     let h = this.h;
     let c10 = extra.parentNode;
@@ -516,6 +527,7 @@ exports[`t-slot directive slots are rendered with proper context, part 3 3`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let scope = Object.create(context);
     let h = this.h;
     let c10 = extra.parentNode;
@@ -570,6 +582,7 @@ exports[`t-slot directive slots are rendered with proper context, part 4 2`] = `
 "function anonymous(context, extra
 ) {
     // Template name: \\"slot_default_template\\"
+    let parent = extra.parent;
     let scope = Object.create(context);
     let h = this.h;
     let c4 = extra.parentNode;

tests/component/slots.test.ts

@@ -1118,4 +1118,35 @@ describe("t-slot directive", () => {
 
     expect(env.qweb.templates[Toggler.template].fn.toString()).toMatchSnapshot();
   });
+
+  test("t-slot within dynamic t-call", async () => {
+    let child;
+    class Child extends Component {
+      static template = xml`<div class="child"/>`;
+      constructor(...args) {
+        super(...args);
+        child = this;
+      }
+    }
+
+    class Slotted extends Component {
+      static template = xml`<div class="slotted"><t t-slot="default" /></div>`;
+    }
+
+    class UsingTcallInSlotted extends Component {
+      tcallTemplate =  xml`<div class="slot"><Child/></div>`;
+      static template = xml`
+      <div>
+        <Slotted>
+          <t t-call="{{ tcallTemplate }}"/>
+        </Slotted>
+      </div>`;
+      static components = { Slotted , Child };
+    }
+
+    await mount(UsingTcallInSlotted, {target: fixture});
+
+    expect(child.__owl__.parent).toBeInstanceOf(Slotted);
+    expect(fixture.innerHTML).toBe(`<div><div class="slotted"><div class="slot"><div class="child"></div></div></div></div>`);
+  });
 });