Revert of [regexp] implement /ui to mirror the implementation for /i.

test/mjsunit/harmony/unicode-regexp-ignore-case-noi18n.js

Index: test/mjsunit/harmony/unicode-regexp-ignore-case-noi18n.js
diff --git a/test/mjsunit/harmony/unicode-regexp-ignore-case-noi18n.js b/test/mjsunit/harmony/unicode-regexp-ignore-case-noi18n.js
index b8e57ac25c15b7f331b2e88244abce8eb36c8918..a4cb9dc337f9e2305e658193e75f22fc7e5a5421 100644
--- a/test/mjsunit/harmony/unicode-regexp-ignore-case-noi18n.js
+++ b/test/mjsunit/harmony/unicode-regexp-ignore-case-noi18n.js
@@ -50,3 +50,10 @@ assertTrue(/\u1f6b/ui.test("\u1f63"));
 // Back references.
 assertNull(/(.)\1\1/ui.exec("\u00e5\u212b\u00c5"));
 assertNull(/(.)\1/ui.exec("\u{118aa}\u{118ca}"));
+
+
+// Non-Latin1 maps to Latin1.
+assertNull(/^\u017F/ui.exec("s"));
+assertNull(/^\u017F/ui.exec("s\u1234"));
+assertNull(/^a[\u017F]/ui.exec("as"));
+assertNull(/^a[\u017F]/ui.exec("as\u1234"));