refactor(core): remove duplicate check in defaultStyleSanitizer (angular#26947)

PR Close angular#26947

Author: gkalpak

packages/core/src/sanitization/sanitization.ts

@@ -172,8 +172,7 @@ export function sanitizeUrlOrResourceUrl(unsafeUrl: any, tag: string, prop: stri
 export const defaultStyleSanitizer = (function(prop: string, value?: string): string | boolean {
   if (value === undefined) {
     return prop === 'background-image' || prop === 'background' || prop === 'border-image' ||
-        prop === 'filter' || prop === 'filter' || prop === 'list-style' ||
-        prop === 'list-style-image';
+        prop === 'filter' || prop === 'list-style' || prop === 'list-style-image';
   }
 
   return sanitizeStyle(value);
@@ -200,4 +199,4 @@ export function validateAttribute(name: string) {
 function getSanitizer(): Sanitizer|null {
   const lView = getLView();
   return lView && lView[SANITIZER];
-}
+}