Use watch parameter for css-vars-ponyfill and remove the global variable

Signed-off-by: Julius Härtl <jus@bitgrid.net>

core/js/js.js

@@ -1350,11 +1350,6 @@ function initCore() {
 		$('html').addClass('edge');
 	}
 
-	// css variables fallback for IE
-	if (msie > 0 || trident > 0) {
-		cssVars();
-	}
-
 	$(window).on('unload.main', function() {
 		OC._unloadCalled = true;
 	});

core/src/globals.js

@@ -48,13 +48,16 @@ import 'snap.js/dist/snap'
 import 'strengthify'
 import 'strengthify/strengthify.css'
 
+cssVars({
+	watch: true
+})
+
 window['_'] = _
 window['$'] = $
 window['autosize'] = autosize
 window['Backbone'] = Backbone
 window['Clipboard'] = ClipboardJS
 window['ClipboardJS'] = ClipboardJS
-window['cssVars'] = cssVars
 window['dav'] = dav
 window['DOMPurify'] = DOMPurify
 window['Handlebars'] = Handlebars