build: fix lint failure

Fixes a lint failure due to a few PRs landing in at the same time where one introduces a new lint rule.

Author: crisbeto

src/material-experimental/mdc-list/interactive-list-base.ts

@@ -89,8 +89,7 @@ export abstract class MatInteractiveListBase<T extends MatListItemBase>
   }
 
   ngAfterViewInit() {
-    // TODO: Replace with `ngDevMode` build time check once #20146 is available.
-    if (isDevMode() && !this._foundation) {
+    if ((typeof ngDevMode === 'undefined' || ngDevMode) && !this._foundation) {
       throw Error('MDC list foundation not initialized for Angular Material list.');
     }
 

src/material-experimental/mdc-list/selection-list.ts

@@ -98,7 +98,7 @@ export class MatSelectionList extends MatInteractiveListBase<MatListOption>
     const newValue = coerceBooleanProperty(value);
 
     if (newValue !== this._multiple) {
-      if (isDevMode() && this._initialized) {
+      if ((typeof ngDevMode === 'undefined' || ngDevMode) && this._initialized) {
         throw new Error(
           'Cannot change `multiple` mode of mat-selection-list after initialization.');
       }