fix(material/tabs): remove dependency on NgClass (#28875)

We can set classes directly through `[class]` instead of having to import `NgClass`.

(cherry picked from commit b3298f1)

Author: crisbeto

src/material/tabs/tab-group.html

@@ -20,7 +20,7 @@
         [attr.aria-label]="tab.ariaLabel || null"
         [attr.aria-labelledby]="(!tab.ariaLabel && tab.ariaLabelledby) ? tab.ariaLabelledby : null"
         [class.mdc-tab--active]="selectedIndex === i"
-        [ngClass]="tab.labelClass"
+        [class]="tab.labelClass"
         [disabled]="tab.disabled"
         [fitInkBarToContent]="fitInkBarToContent"
         (click)="_handleClick(tab, tabHeader, i)"
@@ -72,7 +72,7 @@
                  [attr.aria-labelledby]="_getTabLabelId(i)"
                  [attr.aria-hidden]="selectedIndex !== i"
                  [class.mat-mdc-tab-body-active]="selectedIndex === i"
-                 [ngClass]="tab.bodyClass"
+                 [class]="tab.bodyClass"
                  [content]="tab.content!"
                  [position]="tab.position!"
                  [origin]="tab.origin"

src/material/tabs/tab-group.ts

@@ -37,7 +37,6 @@ import {startWith} from 'rxjs/operators';
 import {CdkMonitorFocus, FocusOrigin} from '@angular/cdk/a11y';
 import {MatTabBody} from './tab-body';
 import {CdkPortalOutlet} from '@angular/cdk/portal';
-import {NgClass} from '@angular/common';
 import {MatTabLabelWrapper} from './tab-label-wrapper';
 import {Platform} from '@angular/cdk/platform';
 
@@ -89,7 +88,6 @@ const ENABLE_BACKGROUND_INPUT = true;
     MatTabHeader,
     MatTabLabelWrapper,
     CdkMonitorFocus,
-    NgClass,
     MatRipple,
     CdkPortalOutlet,
     MatTabBody,

src/material/tabs/tab.ts

@@ -90,16 +90,10 @@ export class MatTab implements OnInit, OnChanges, OnDestroy {
    */
   @Input('aria-labelledby') ariaLabelledby: string;
 
-  /**
-   * Classes to be passed to the tab label inside the mat-tab-header container.
-   * Supports string and string array values, same as `ngClass`.
-   */
+  /** Classes to be passed to the tab label inside the mat-tab-header container. */
   @Input() labelClass: string | string[];
 
-  /**
-   * Classes to be passed to the tab mat-tab-body container.
-   * Supports string and string array values, same as `ngClass`.
-   */
+  /** Classes to be passed to the tab mat-tab-body container. */
   @Input() bodyClass: string | string[];
 
   /** Portal that will be the hosted content of the tab */