[TIMOB-26179] Check for property existence using hasProperty

[janvennemann]

JIRA: https://jira.appcelerator.org/browse/TIMOB-26179

Optional Description:
Implements the hasProperty callback to properly check for property existence in our proxy objects. Without this callback getProperty is which results in property checks always returning true.

@hansemannn Not sure if this implies a breaking change or can just be considered as a re-definition of previously undefined behavior.

[build]

	Fails
🚫	Tests have failed, see below for more information.

	Messages
📖	💾 Here's the generated SDK zipfile.

Tests:

Classname	Name	Time	Error
ios.Titanium.UI.WebView	userAgent	10.009	file:///Users/build/Librar

Generated by 🚫 dangerJS

[hansemannn]

LGTM. But please add a unit-test for it since it should be somehow testable from our proxy implementation. Also, do you have a practical use case for this that is worth mentioning?

[sgtcoolguy]

collapse the last few lines down to:

return result != nil;

[sgtcoolguy]

I think it'd be pretty easy to add a quick unit test that generated a proxy and then just tested for a non-existent and existing own property. I believe iOS always returned true before?

var label = Ti.UI.createLabel();
should(label.hasOwnProperty('madeup')).eql(false);
should(label.hasOwnProperty('text')).eql(true);
label.madeup = 123;
should(label.hasOwnProperty('madeup')).eql(true);