IonRouterOutlet.pop() doesn't properly update the browser navigation history

# Bug Report

**Ionic Info**
```
Ionic:

ionic (Ionic CLI) : 4.1.1 (C:\Users\User\AppData\Roaming\npm\node_modules\ionic)
Ionic Framework : @ionic/angular 4.0.0-beta.5
@angular-devkit/core : 0.7.5
@angular-devkit/schematics : 0.7.5
@angular/cli : 6.1.5
@ionic/ng-toolkit : 1.0.7
@ionic/schematics-angular : 1.0.5

Cordova:

cordova (Cordova CLI) : 7.1.0
Cordova Platforms : android 6.3.0
Cordova Plugins : not available

System:

Android SDK Tools : 26.1.1 (C:\Android\sdk\)
NodeJS : v8.9.1 (C:\Program Files\nodejs\node.exe)
npm : 5.5.1
```

**Describe the Bug**
When we use `IonRouterOutlet.pop()` to go back to previous url, it seems that it does take us to previous page but doesn't update the browser navigation history.

**Steps to Reproduce**
For example, if we follow this path Page A > Page B > Page C and then use `IonRouterOutlet.pop()` in Page C to go back to Page B, it will take us to previous page i.e. Page B but now if we press Browser back button once nothing will happen, if we press it another time it will take us to Page A. If the browser history was updated properly, pressing Browser back button once should take us to Page A.

As a result,

- Navigation has unexpected behaviour
- Breaks Angular relative routes

**Expected Behavior**
Navigation should work properly.