Initial bound values are not fully propagated [can 4.0 pre]

[Alfredo-Delgado]

In this example, <source-component /> will always set a default person -- undefined is not allowed.

<h3>Hello [demoContext/{{./person}}]</h3>
  
<source-component person:bind="./person" />
<clear-button person:bind="./person" />

When the app loads, the default is only present in <source-component />. It works as expected when the value is set afterward.

Here's the code: https://codepen.io/Alfredo-Delgado/pen/OOxqog?editors=1011

Related to #325

[Sinjhin]

This will be reverted to the regular 3.x behavior with this commit to major: eff681b

For explaination, see: #325 (comment)