[Bugfix] LazyGet of aliasDescriptor should respected the aliased...

[stefanpenner]

... cache preference.

• WIP
• write test
• get feedback on approach.
• https://github.com/emberjs/ember.js/blob/master/packages/ember-metal/lib/computed.js#L504 should be also be aware of this.
• alias('foo.baz') where foo.baz is another descriptor
• audit other places that reach into meta (like array/reduce computed)
• add a test for lengthy alias chains
• Ember.lazyGet

add explicit tests for:

• Descriptor.prototype.getCache (include UNDEFINED case)
• Descriptor.prototype.lazyGet
• Descriptor.prototype.isCacheable

[stefanpenner]

ya, i just opened pandoras box...

[wagenet]

@stefanpenner what's the status here?

[stefanpenner]

@wagenet, this opened pandoras box @krisselden is working on the solution.