[Bug] Label.Text comments not allowed after the first non-whitespace character.

Description

<Label.Text> tag does not allow comments after the first non-whitespace character

Steps to Reproduce

1. Clone repository here: https://github.com/jcummings2/LabelTextBug
2. Try to build project

Alternately, you may also change any existing Label in a project to use the <Label.Text> tag like so:

<Label>
    <Label.Text>
Text can go here but you can't add a comment after it
<!-- Comment not allowed after first non-whitespace character -->
    </Label.Text>
</Label>

Expected Behavior

All comments should be ignored, regardless of where they occur.

Actual Behavior

XAML does not compile if there is a comment after the first non-whitespace character. The errors are:

• On mac: Error: Specified cast is not valid.
• On windows: Unable to cast object of type 'Xamarin.Forms.Xaml.ListNode' to type 'Xamarin.Forms.Xaml.IElementNode'.

Basic Information

• Version with issue: 4.3.0.908675 (latest as of this writing)
• Last known good version: ?
• IDE: VS Pro for Mac 8.4 (Build 2535) and VS Pro for Windows 16.4.0
• Platform Target Frameworks:
  • iOS: 8.0
  • Android: 9.0
• Android Support Library Version: N/A
• Nuget Packages: N/A
• Affected Devices: N/A never gets that far

Screenshots

N/A

Reproduction Link

https://github.com/jcummings2/LabelTextBug/blob/master/LabelTextBug/MainPage.xaml#L6