fix deliver() for native props on chrome

[wkeese]

On Chrome and old iOS etc., we track updates to native properties via MutationObserver. This means that we hear about the updates asynchronously, even if the app calls deliver().

As a corollary, initial processing for parameters like value in new Switch({value: ...}) also happen asynchronously, even though deliver() is called on creation. (Inconsistently, we handle <d-switch value=....> synchronously.)

I think this can be fixed by using the code in CustomElement#createdCallback():

// Call custom setters for initial values of attributes with shadow properties (dir, tabIndex, etc)
attrs.forEach(function (attrName) {
    if (this.hasAttribute(attrName)) { // initial value was specified
        var value = this.getAttribute(attrName);
        this.removeAttribute(attrName);
        setterMap[attrName].call(this, value); // call custom setter
    }
}, this);

And doing it also/instead in deliver().

Then clean up setTimeout() "workarounds" in test files like deliteful/tests/unit/ToggleButton.js.