fixup! fix(material-experimental/mdc-form-field): use a CSS var for the floating label scale

Author: mmalerba

src/material-experimental/mdc-form-field/directives/notched-outline.ts

@@ -35,7 +35,7 @@ import {
   encapsulation: ViewEncapsulation.None,
 })
 export class MatFormFieldNotchedOutline implements AfterViewInit {
-  /** Width of the notch. */
+  /** Width of the label (original scale) */
   @Input('matFormFieldNotchedOutlineLabelWidth') labelWidth: number = 0;
 
   /** Whether the notch should be opened. */

src/material-experimental/mdc-form-field/form-field.ts

@@ -267,7 +267,7 @@ export class MatFormField
   /** State of the mat-hint and mat-error animations. */
   _subscriptAnimationState = '';
 
-  /** Width of the outline notch. */
+  /** Width of the label element (at scale=1). */
   _labelWidth = 0;
 
   /** Gets the current form field control */