**Environment** - tns-core-modules modules: 6.0.0-rc-2019-06-28-175837-02 **Describe the bug** <!-- A clear and concise description of what the bug is. Please, explain whether it's a build time error or a runtime error. More detailed logs can be easily obtained by following the instructions in this guide: https://docs.nativescript.org/get-support#how-to-obtain-diagnostic-reports. --> Setting `iconSource` on `TabStripItem` does not work for iOS. **To Reproduce** - a [sample tabs page](https://github.com/NativeScript/NativeScript/commit/808fbd414d6a01ebad34fcdbbc816af82223b858). **Expected** Icons to be shown along with the **titles**. **Actual** 
Environment
Describe the bug
Setting
iconSourceonTabStripItemdoes not work for iOS.To Reproduce - a sample tabs page.
Expected
Icons to be shown along with the titles.
Actual