fix($compile): Allow literals in isolate scope references

When a component uses an isolate scope reference
and the the component is used with an object literal
a new object is created on every evaluation.
Therefore the compiler needs to compare
the values of the parent and the isolate scope
using object equality and not object reference
equality.

Fixes #5296.
Merge branch 'master' of https://github.com/angular/angular.js
componentizd!