Sync Protractor with an Angular app hosted inside an iframe by a non-Angular website

I'm having trouble accessing elements via methods such as by.binding().

The project setup is as follows:

Non-angular website
|
--> Iframe
    |
    --> Angular app

Here's a snippet of what I'm trying to do:

// Disable sync
browser.ignoreSynchronization = true;

// Navigate to non-angular website
browser.driver.get('http://non-angular.com');

// Switch to angular app (inside the iframe)
browser.switchTo().frame('angular-iframe');

// Search for an element
browser.driver.findElement(by.id('title')); // -> Works

element(by.binding('model.title')); // -> Fails 
UnknownError: unknown error: [ng:test] no injector found for element argument to getTestability

Any idea of what I'm missing here?

Copyright Notice：Content Author:「Pablo」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/30597802/sync-protractor-with-an-angular-app-hosted-inside-an-iframe-by-a-non-angular-web