Bump to v4.10.0.

_stringSize.js

@@ -1,3 +1,5 @@
+var reHasComplexSymbol = require('./_reHasComplexSymbol');
+
 /** Used to compose unicode character classes. */
 var rsAstralRange = '\\ud800-\\udfff',
     rsComboMarksRange = '\\u0300-\\u036f\\ufe20-\\ufe23',
@@ -24,9 +26,6 @@ var reOptMod = rsModifier + '?',
 /** Used to match [string symbols](https://mathiasbynens.be/notes/javascript-unicode). */
 var reComplexSymbol = RegExp(rsFitz + '(?=' + rsFitz + ')|' + rsSymbol + rsSeq, 'g');
 
-/** 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 + ']');
-
 /**
  * Gets the number of symbols in `string`.
  *