Data binding in embedded template doesn't work

[szolo]

Issue 1

Steps to reproduce

1. Import the project: https://github.com/vaadin/designer/files/2778287/skeleton-starter-flow.zip
2. Open my-view.html in Preview

Actual behaviour

The dom-repeat contents inside the embedded component are not rendered:

Expected behaviour

The dom-repeat is bound correctly to the data and it's shown:

Issue 2

Steps to reproduce

1. Import the project: https://github.com/vaadin/designer/files/2778287/skeleton-starter-flow.zip
2. Open my-view.html in Edit

Actual behaviour

The dom-repeat inside the embedded component is rendered:

Expected behaviour

The dom-repeat is not rendered, but the contents is displayed.

IDE, Designer and OS version

Windows 10, Designer 4.1.1, latest IntelliJ.

Notes

Originally reported by @anssit. I have a feeling that it's somehow related to the property, which is used in data binding. Since it's item it means that it's not declared explicitly in the corresponding web component.

I also investigate a bit and it looks like that in preview mode for main-view our artificial _internalDesignerGetTextContent is still used. This is not the case for product-view: it contains only data bindings in preview mode. This behavior needs to be investigated and aligned.

[anssit]

skeleton-starter-flow.zip
A simpler test project. See my-view.html in preview mode: Array items are not displayed.