[searchcursor addon] Normalize strings when supported

Issue #4784

Author: marijnh

addon/search/searchcursor.js

@@ -115,8 +115,14 @@
     }
   }
 
-  function doFold(str) { return str.toLowerCase() }
-  function noFold(str) { return str }
+  var doFold, noFold
+  if (String.prototype.normalize) {
+    doFold = function(str) { return str.normalize("NFD").toLowerCase() }
+    noFold = function(str) { return str.normalize("NFD") }
+  } else {
+    doFold = function(str) { return str.toLowerCase() }
+    noFold = function(str) { return str }
+  }
 
   // Maps a position in a case-folded line back to a position in the original line
   // (compensating for codepoints increasing in number during folding)