Environment
Provide version numbers for the following components (information can be retrieved by running tns info in your project folder or by inspecting the package.json of the project):

• CLI: 5.3
• iOS Runtime: 5.1.0
• NativeScript-Angular: 7.1.0
• Angular: 7.1.0

Describe the bug
On iOS, when a GridLayout child element is positioned using "col" and "row" where the positioning is calculated at runtime---eg [col]="idx % 2" [row]="idx / 2"---this causes a crash on iOS with a TypeError: undefined is not an object (evaluating 'rowGroup.getIsAuto').

To Reproduce

1. Create a NS Angular project.
2. Create a component with an arbitrary set of "items":

export class ItemsComponent {
    items = ["Item 1", "Item 2", "Item 3"];
}

1. In the component's template, attempt to display the items in a GridLayout, calculating the 'col' and 'row' dynamically:

<GridLayout columns="*, *" rows="auto, auto">
    <StackLayout *ngFor="let item of items; let idx = index"
        [col]="idx % 2" [row]="idx / 2">
        <Label [text]="item"></Label>
    </StackLayout>
</GridLayout>

1. When running the app, on iOS, the app will crash.

Expected behavior
The items should be displayed nicely in a grid, evenly spaced horizontally and auto-spaced vertically.

Sample project
https://github.com/sbknick/ns-ios-dynamicpositionedgridlayout

Additional context
On Android, this functions as expected.