[FIX] props validation: does not crash with t-call-context

The code for props validation assumed that the rendering context was a
component.  This was actually true when it was written, but is no longer
true since t-call-context was introduced.

Because of that, it would crash when trying to access the internals of
the component, such as the static components object.

The fix is simple: instead of passing the context to the props
validation code, which can now be anything, we pass the component node,
which is guaranteed to give a reference to the component (and also to
the app).  This also make the code slightly simpler.

closes #1261

src/compiler/code_generator.ts

@@ -1188,7 +1188,7 @@ export class CodeGenerator {
     }
 
     if (this.dev) {
-      this.addLine(`helpers.validateProps(${expr}, ${propVar!}, ctx);`);
+      this.addLine(`helpers.validateProps(${expr}, ${propVar!}, node);`);
     }
 
     if (block && (ctx.forceNewBlock === false || ctx.tKeyExpr)) {

src/runtime/app.ts

@@ -66,7 +66,7 @@ export class App<
   mount(target: HTMLElement, options?: MountOptions): Promise<Component<P, E> & InstanceType<T>> {
     App.validateTarget(target);
     if (this.dev) {
-      validateProps(this.Root, this.props, { __owl__: { app: this } });
+      validateProps(this.Root, this.props, { app: this });
     }
     const node = this.makeNode(this.Root, this.props);
     const prom = this.mountNode(node, target, options);

src/runtime/template_helpers.ts

@@ -207,11 +207,11 @@ function multiRefSetter(refs: RefMap, name: string): RefSetter {
  * visit recursively the props and all the children to check if they are valid.
  * This is why it is only done in 'dev' mode.
  */
-export function validateProps<P>(name: string | ComponentConstructor<P>, props: P, parent?: any) {
+export function validateProps<P>(name: string | ComponentConstructor<P>, props: P, node?: any) {
   const ComponentClass =
     typeof name !== "string"
       ? name
-      : (parent.constructor.components[name] as ComponentConstructor<P> | undefined);
+      : (node.component.constructor.components[name] as ComponentConstructor<P> | undefined);
 
   if (!ComponentClass) {
     // this is an error, wrong component. We silently return here instead so the
@@ -221,7 +221,7 @@ export function validateProps<P>(name: string | ComponentConstructor<P>, props:
 
   const schema = ComponentClass.props;
   if (!schema) {
-    if (parent.__owl__.app.warnIfNoStaticProps) {
+    if (node.app.warnIfNoStaticProps) {
       console.warn(`Component '${ComponentClass.name}' does not have a static props description`);
     }
     return;