More fixes for IE11

Author: slevithan

src/xregexp.js

@@ -67,16 +67,19 @@ function hasNativeFlag(flag) {
         // Can't use regex literals for testing even in a `try` because regex literals with
         // unsupported flags cause a compilation error in IE
         new RegExp('', flag);
+
+        // Work around a broken/incomplete IE11 polyfill for sticky introduced in core-js 3.6.0
+        if (flag === 'y') {
+            // Using function to avoid babel transform to regex literal
+            const gy = (() => 'gy')();
+            const incompleteY = '.a'.replace(new RegExp('a', gy), '.') === '..';
+            if (incompleteY) {
+                isSupported = false;
+            }
+        }
     } catch (exception) {
         isSupported = false;
     }
-    // Work around a broken/incomplete IE11 polyfill for sticky introduced in core-js 3.6.0
-    if (flag === 'y') {
-        const incompleteY = '.a'.replace(new RegExp('a', 'gy'), '.') === '..';
-        if (incompleteY) {
-            isSupported = false;
-        }
-    }
     return isSupported;
 }
 // Check for ES6 `u` flag support

tests/helpers/h.js

@@ -22,3 +22,10 @@ global.hasStrictMode = (function() {
 
     return !this;
 }());
+
+// Naive polyfill of String.prototype.repeat
+if (!String.prototype.repeat) {
+    String.prototype.repeat = function(count) {
+        return count ? Array(count + 1).join(this) : '';
+    };
+}

tests/perf/index.html

@@ -24,7 +24,7 @@
             var match = /[?&]version=([^&]+)/.exec(location.search);
             var version = match ? match[1] : null;
             var knownVersion = {
-                '4.3.0': true,
+                '4.3.1': true,
                 '4.2.4': true,
                 '4.2.3': true,
                 '4.2.0': true,