So we can't remove the if: dotvvm.isSpaRead condition

...but, we can replace it with `if: true`, which does not have the unwanted effect of hiding
the content before everything loads.

The reson is that ko.bindingContext/updateContext is pureComputed and won't update
$data right after we replace the viewModel. We need someone to call `context[contextSubscribable]` to update it.
Any binding will do that, but only after it's initialized, so the initialization will fail on
"Property X was not defined".

The pureComputed was introduced in knockout/knockout@0ac7010.
It's probably not a knockout bug, as it's not possible to reproduce without our hacks with
applyBindings in restoreUpdatedControls. If we used a binding handler for this, everything
would be fine.

Author: exyi

src/Framework/Framework/Controls/SpaContentPlaceHolder.cs

@@ -109,6 +109,7 @@ protected internal override void OnPreRender(IDotvvmRequestContext context)
 
         protected override void AddAttributesToRender(IHtmlWriter writer, IDotvvmRequestContext context)
         {
+            writer.AddKnockoutDataBind("if", "true"); // yep, go ahead and try to remove it
             base.AddAttributesToRender(writer, context);
         }
 

src/Framework/Framework/Resources/Scripts/postback/updater.ts

@@ -67,6 +67,7 @@ export function updateViewModelAndControls(resultObject: any, updateTypeInfo: (t
 
     // we have to update knockout viewmodel before we try to apply new data into the observables
     getStateManager().doUpdateNow()
+    ko.tasks.runEarly()
 
     // add new updated controls
     restoreUpdatedControls(resultObject, updatedControls);