Implements ES6 String.prototype.normalize method.

src/string.js

Index: src/string.js
diff --git a/src/string.js b/src/string.js
index 14b44ca41f3d7f248a5756b54983f09ab3a55c8e..809d24f033fdc70b0547fe47c0ed887fa855c3ff 100644
--- a/src/string.js
+++ b/src/string.js
@@ -200,6 +200,31 @@ function StringMatch(regexp) {
 }
 
 
+var NORMALIZATION_FORMS = ['NFC', 'NFD', 'NFKC', 'NFKD'];
+
+
+// ECMA-262 v6, section 21.1.3.12
+//
+// For now we do nothing, as proper normalization requires big tables.
+// If Intl is enabled, then i18n.js will override it and provide the the
+// proper functionality.
+function StringNormalize(form) {
+  if (IS_NULL_OR_UNDEFINED(this) && !IS_UNDETECTABLE(this)) {

[mathias, 2014/01/29 09:05:55]

While this is correct, it might be better to just use the
`CHECK_OBJECT_COERCIBLE` macro.

+    throw MakeTypeError("called_on_null_or_undefined",
+                        ["String.prototype.localeCompare"]);

[mathias, 2014/01/29 09:05:55]

s/localeCompare/normalize/

+  }
+
+  var form = form ? TO_STRING_INLINE(form) : 'NFC';
+  var normalizationForm = NORMALIZATION_FORMS.indexOf(form);
+  if (normalizationForm === -1) {
+    throw new $RangeError('The normalization form should be one of '
+        + NORMALIZATION_FORMS.join(', ') + '.');
+  }
+
+  return %_ValueOf(this);
+}
+
+
 // This has the same size as the lastMatchInfo array, and can be used for
 // functions that expect that structure to be returned.  It is used when the
 // needle is a string rather than a regexp.  In this case we can't update
@@ -984,6 +1009,7 @@ function SetUpString() {
     "lastIndexOf", StringLastIndexOf,
     "localeCompare", StringLocaleCompare,
     "match", StringMatch,
+    "normalize", StringNormalize,
     "replace", StringReplace,
     "search", StringSearch,
     "slice", StringSlice,