fixup! fix(material/slider): form control w/ initial disabled state

Author: wagnermaciel

src/material/slider/slider-input.ts

@@ -278,6 +278,7 @@ export class MatSliderThumb implements _MatSliderThumb, OnDestroy, ControlValueA
 
     // If this or the parent slider is disabled, just make everything disabled.
     if (this.disabled !== this._slider.disabled) {
+      // The MatSlider setter for disabled will relay this and disable both inputs.
       this._slider.disabled = true;
     }