Fix failing string test in Chrome.

Author: savetheclocktower

src/prototype/lang/string.js

@@ -38,6 +38,13 @@ Object.extend(String.prototype, (function() {
     var template = new Template(replacement);
     return function(match) { return template.evaluate(match) };
   }
+  
+  // In some versions of Chrome, an empty RegExp has "(?:)" as a `source`
+  // property instead of an empty string.
+  function isNonEmptyRegExp(regexp) {
+    return regexp.source && regexp.source !== '(?:)';
+  }
+
 
   /**
    *  String#gsub(pattern, replacement) -> String
@@ -93,8 +100,8 @@ Object.extend(String.prototype, (function() {
 
     if (Object.isString(pattern))
       pattern = RegExp.escape(pattern);
-
-    if (!(pattern.length || pattern.source)) {
+      
+    if (!(pattern.length || isNonEmptyRegExp(pattern))) {
       replacement = replacement('');
       return replacement + source.split('').join(replacement) + replacement;
     }

test/unit/string_test.js

@@ -46,9 +46,9 @@ new Test.Unit.Runner({
       'ウィメンズ2007\nクルーズコレクション'.gsub('\n','<br/>'));
 
     this.assertEqual('barfbarobarobar barbbarobarobar barbbarobarzbar',
-      source.gsub('', 'bar'));
+      source.gsub('', 'bar'), 'empty string');
     this.assertEqual('barfbarobarobar barbbarobarobar barbbarobarzbar',
-      source.gsub(new RegExp(''), 'bar'));
+      source.gsub(new RegExp(''), 'bar'), 'empty regexp');
   },
 
   testGsubWithReplacementTemplateString: function() {