Allow faster lookup path that does not use undefinedObserves

[phillipskevin]

The current Scope.prototype._read does a lot of work to keep track of all observables that were checked when looking for a property:

can-view-scope/can-view-scope.js

Lines 320 to 323 in 8db47da

	// The **value was not found**, return `undefined` for the value.
	// Make sure we listen to everything we checked for when the value becomes defined.
	// Once it becomes defined, we won't have to listen to so many things.
	Observation.addAll(undefinedObserves);

When most lookups will not walk the scope, this is a lot of unnecessary work.

We should make a faster path that does not do all of this and eventually remove this code.