[Ionic v4] Missing disabled styles on ion-fab-button if disabled

[peterpeterparker]

Ionic Info
@ionic/angular: "4.0.0-alpha.12"

Describe the Bug
When an ion-button is disabled, the following styles is used

.button-native[disabled] {
     cursor: default;
     opacity: .5;
     pointer-events: none;
}

The same attributes aren't applied to ion-fab-button when these are disabled too

Related Code

<ion-fab-button disabled/>

Expected Behavior
As ion-button, when ion-fab-button are set as disabled, they should inherit the same disabled style classes

[ionitron-bot]

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