Get Source Code from Webview (VB for Metro) - vb.net

Question

I'm Making a Windows Phone's app that I can, From a webview called "DebWeb", get the ClassRoom of a specific class. The DebWeb load the site where is all the classRooms, but I want to make that my App search just my class.
Before I made an app with almost the same objetive (search the Name of a App from the Source Code), but it was made from VB for PC, now I'm working on VB for Metro (or for App Store) and I can't use the same code.
For example, On VB for PC I can use:
Dim EHTML = DebWeb.Document.All.Item(1)
Dim sourceString As String = EHTML.InnerHtml
'Use Regex Match to search from SourceString"
But on VB for Metro it's shows me the " 'Document' is not a member of 'Windows.UI.XAML.Controls.WebView' " error, so I can't get the Source Code from the page and I can't look for the ClassRoom.
I Looked on the MSDN page about Webview but the most close thing that I can do is to get the "DocumentTittle", but not the content.
This is my code, everything "works" except the "Source" variable:
Dim Source = DebWeb.[Control] 'Here is where I need the Control to get the SourceCode
Dim m As System.Text.RegularExpressions.Match = System.Text.RegularExpressions.Regex.Match(Source.ToString, _
"DERECHO CONSTITUCIONAL", _
System.Text.RegularExpressions.RegexOptions.IgnoreCase)
Edited with my Entire code:
Private Sub MainPage_Loaded(sender As Object, e As RoutedEventArgs) Handles Me.Loaded
Dim URL As String = "http://goo.gl/uqohKw"
Me.DebWeb.Navigate(New Uri(URL))
End Sub
Private Sub DebWeb_LoadCompleted(ByVal sender As Object, ByVal e As WebViewNavigationCompletedEventArgs)
LListo.Text = "Listo!"
Dim html As String = DebWeb.InvokeScriptAsync("eval", New String() {"document.documentElement.outerHTML;"}).ToString
Dim Source = html
Dim m As System.Text.RegularExpressions.Match = System.Text.RegularExpressions.Regex.Match(Source.ToString, _
"LECTURA CRÍTICA", _
System.Text.RegularExpressions.RegexOptions.IgnoreCase)
If (m.Success) Then
Dim key As String = m.Groups(1).Value
End If
End Sub

Answer 1

Something like this?
Private Sub Button_Click(sender As Object, e As RoutedEventArgs)
Try
Dim html As String = Await myWebView.InvokeScriptAsync("eval", New String() {"document.documentElement.outerHTML;"})
Catch ex As Exception
End Try
End Sub
More Info here