diff --git a/resources/skins.vector.js/setupIntersectionObservers.js b/resources/skins.vector.js/setupIntersectionObservers.js
index 7097d7b9d..c55675bef 100644
--- a/resources/skins.vector.js/setupIntersectionObservers.js
+++ b/resources/skins.vector.js/setupIntersectionObservers.js
@@ -283,18 +283,12 @@ const setupTableOfContents = ( tocElement, bodyContent, initSectionObserverFn )
  * @return {void}
  */
 const main = () => {
-	const isIntersectionObserverSupported = 'IntersectionObserver' in window;
-
 	//
 	//  Table of contents
 	//
 	const tocElement = document.getElementById( TOC_ID );
 	const bodyContent = document.getElementById( BODY_CONTENT_ID );
-
-	const isToCUpdatingAllowed = isIntersectionObserverSupported &&
-		window.requestAnimationFrame;
-	const tableOfContents = isToCUpdatingAllowed ?
-		setupTableOfContents( tocElement, bodyContent, initSectionObserver ) : null;
+	const tableOfContents = setupTableOfContents( tocElement, bodyContent, initSectionObserver );
 
 	//
 	// Sticky header
@@ -311,8 +305,7 @@ const main = () => {
 		!!stickyIntersection &&
 		!!userLinksDropdown &&
 		allowedNamespace &&
-		allowedAction &&
-		isIntersectionObserverSupported;
+		allowedAction;
 
 	const { showStickyHeader } = initStickyHeaderABTests(
 		ABTestConfig,
diff --git a/resources/skins.vector.legacy.js/collapsibleTabs.js b/resources/skins.vector.legacy.js/collapsibleTabs.js
index 4f95e023a..aa0f2b65f 100644
--- a/resources/skins.vector.legacy.js/collapsibleTabs.js
+++ b/resources/skins.vector.legacy.js/collapsibleTabs.js
@@ -11,7 +11,6 @@
 function init() {
 	/** @type {boolean|undefined} */ let boundEvent;
 	const isRTL = document.documentElement.dir === 'rtl';
-	const rAF = window.requestAnimationFrame || setTimeout;
 
 	// Mark the tabs which can be collapsed under the more menu
 	// eslint-disable-next-line no-jquery/no-global-selector
@@ -43,12 +42,12 @@ function init() {
 		if ( !boundEvent ) {
 			boundEvent = true;
 			$( window ).on( 'resize', mw.util.debounce( () => {
-				rAF( $.collapsibleTabs.handleResize );
+				requestAnimationFrame( $.collapsibleTabs.handleResize );
 			}, 10 ) );
 		}
 
 		// call our resize handler to setup the page
-		rAF( $.collapsibleTabs.handleResize );
+		requestAnimationFrame( $.collapsibleTabs.handleResize );
 		// When adding new links, a resize should be triggered (T139830).
 		mw.hook( 'util.addPortletLink' ).add( $.collapsibleTabs.handleResize );
 		return this;
@@ -161,7 +160,7 @@ function init() {
 					$( this ).detach().prependTo( target ).data( 'collapsibleTabsSettings', outerData );
 					$( this ).attr( 'style', 'display: list-item;' );
 					collapsedContainerSettings.shifting = false;
-					rAF( $.collapsibleTabs.handleResize );
+					requestAnimationFrame( $.collapsibleTabs.handleResize );
 				} );
 		},
 		moveToExpanded: function ( $moving ) {
@@ -188,7 +187,7 @@ function init() {
 					.data( 'collapsibleTabsSettings', data )
 					.animate( { width: expandedWidth + 'px' }, 'normal', function () {
 						$( this ).attr( 'style', 'display: block;' );
-						rAF( () => {
+						requestAnimationFrame( () => {
 							// Update the 'expandedWidth' in case someone was brazen enough to
 							// change the tab's contents after the page load *gasp* (T71729). This
 							// doesn't prevent a tab from collapsing back and forth once, but at
diff --git a/resources/skins.vector.search/instrumentation.js b/resources/skins.vector.search/instrumentation.js
index 399ad3543..4578326f9 100644
--- a/resources/skins.vector.search/instrumentation.js
+++ b/resources/skins.vector.search/instrumentation.js
@@ -9,7 +9,6 @@ const INPUT_LOCATION_MOVED = 'header-moved',
 	// mediawiki.searchSuggest performance. Marks and Measures will only be
 	// recorded on the Vector skin and only if browser supported.
 	shouldTestSearchPerformance = !!( window.performance &&
-		!!window.requestAnimationFrame &&
 		!!performance.mark &&
 		!!performance.measure &&
 		!!performance.getEntriesByName &&
diff --git a/skin.json b/skin.json
index 51fd441b3..86ce75fae 100644
--- a/skin.json
+++ b/skin.json
@@ -456,7 +456,8 @@
 				"mediawiki.experiments",
 				"skins.vector.icons.js",
 				"mediawiki.util",
-				"mediawiki.jqueryMsg"
+				"mediawiki.jqueryMsg",
+				"web2017-polyfills"
 			],
 			"messages": [
 				"vector-search-loader",