v4: css: make height of ion-content accessible for childs

[tntwist]

Ionic version: (check one with "x")
(For Ionic 1.x issues, please use https://github.com/ionic-team/ionic-v1)
[ ] 2.x
[ ] 3.x
[x ] 4.x

I'm submitting a ... (check one with "x")
[ ] bug report
[ x] feature request

Current behavior:
Currently childs of ion-content cannot use the height of the ion-content.

Expected behavior:
Childs of ion-content should be able to use the height of of the ion-content.

Steps to reproduce:
Create an simple page with following html template:

<ion-header>
    <ion-toolbar>
        <ion-title>
            <ion-label>Hello, this is a test :)</ion-label>
        </ion-title>
    </ion-toolbar>
</ion-header>
<ion-content [scrollEnabled]="false">
    <ion-slides style="height: 100%;" pager paginationType="bullets">
        <ion-slide>
            <ion-label style="margin-left: 8px;">
                Test slide...
            </ion-label>
        </ion-slide>
    </ion-slides>
</ion-content>

The ion-slides element wont use the 100% height of the parent content.

Related code:
class .scroll-inner in core/src/components/content/content.scss

...
.scroll-inner {
  @include padding(var(--padding-top), var(--padding-end), calc(var(--padding-bottom) + var(--keyboard-offset)), var(--padding-start));

  min-height: 100%;
  box-sizing: border-box;
  -webkit-margin-collapse: discard;
}

The attribute height is missing, so the childs cannot access the parents height.

Other information:
Suggestion: add height: 100% to .scroll-inner class of content.

...
.scroll-inner {
  @include padding(var(--padding-top), var(--padding-end), calc(var(--padding-bottom) + var(--keyboard-offset)), var(--padding-start));

  height: 100%;
  min-height: 100%;
  box-sizing: border-box;
  -webkit-margin-collapse: discard;
}

I´ll make a pull request for thits.

Ionic info::

Ionic:

   ionic (Ionic CLI)          : 4.0.0-rc.11 (C:\Users\nico9\AppData\Roaming\npm\node_modules\ionic)
   Ionic Framework            : @ionic/angular 4.0.0-alpha.9
   @angular-devkit/core       : 0.7.0-rc.1
   @angular-devkit/schematics : 0.7.0-rc.1
   @angular/cli               : 6.0.8
   @ionic/ng-toolkit          : 1.0.0-rc.10
   @ionic/schematics-angular  : 1.0.0-rc.10

Cordova:

   cordova (Cordova CLI) : 8.0.0
   Cordova Platforms     : android 7.0.0 ios 4.5.4

System:

   Android SDK Tools : 25.2.5
   NodeJS            : v10.3.0 (D:\Program Files\nodejs\node.exe)
   npm               : 6.1.0
   OS                : Windows 10

Environment:

   ANDROID_HOME : D:\Development\Android\sdk

[ionitron-bot]

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