Can't dynamically bind to Date.time

(This is about Date.time, but I'm sure it applies to several other fields in Date.)

In the attached test case (compiled with ``-compiler.keep-as3-metadata=Bindable``), the compiler translates ``myDate.time`` to ``myDate.getTime()`` in the JS, which is fine.

But can't dynamically bind (i.e. BindingUtils.bindProperty()) using ``myDate.time``, like you can in Flex.

Is this limitation intentional?

Royale: [TestDate.mxml.txt](https://github.com/apache/royale-asjs/files/5716725/TestDate.mxml.txt)

Flex: [TestDateFlex.mxml.txt](https://github.com/apache/royale-asjs/files/5716726/TestDateFlex.mxml.txt)

Start with the attached TestDate.mxml.txt cases and compile the Royale example with -compiler.keep-as3-metadata=Bindable, then compare the generated JavaScript and behavior with TestDateFlex.mxml.txt. Trace BindingUtils.bindProperty() for Date.time and determine whether dynamic binding should work like Flex or whether the limitation needs to be documented.

Written by the indexing model from the issue text.