Bump to v4.9.0.

split.js

@@ -1,4 +1,19 @@
-define(['./toString'], function(toString) {
+define(['./isRegExp', './_stringToArray', './toString'], function(isRegExp, stringToArray, toString) {
+
+  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
+  var undefined;
+
+  /** Used to compose unicode character classes. */
+  var rsAstralRange = '\\ud800-\\udfff',
+      rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
+      rsComboSymbolsRange = '\\u20d0-\\u20f0',
+      rsVarRange = '\\ufe0e\\ufe0f';
+
+  /** Used to compose unicode capture groups. */
+  var rsZWJ = '\\u200d';
+
+  /** Used to detect strings with [zero-width joiners or code points from the astral planes](http://eev.ee/blog/2015/09/12/dark-corners-of-unicode/). */
+  var reHasComplexSymbol = RegExp('[' + rsZWJ + rsAstralRange  + rsComboMarksRange + rsComboSymbolsRange + rsVarRange + ']');
 
   /**
    * Splits `string` by `separator`.
@@ -20,7 +35,18 @@ define(['./toString'], function(toString) {
    * // => ['a', 'b']
    */
   function split(string, separator, limit) {
-    return toString(string).split(separator, limit);
+    string = toString(string);
+    if (string && (
+          typeof separator == 'string' ||
+          (separator != null && !isRegExp(separator))
+        )) {
+      separator += '';
+      if (separator == '' && reHasComplexSymbol.test(string)) {
+        var strSymbols = stringToArray(string);
+        return limit === undefined ? strSymbols : strSymbols.slice(0, limit < 0 ? 0 : limit);
+      }
+    }
+    return string.split(separator, limit);
   }
 
   return split;