[regexp] implement case-insensitive unicode regexps.

test/mjsunit/mjsunit.status

Index: test/mjsunit/mjsunit.status
diff --git a/test/mjsunit/mjsunit.status b/test/mjsunit/mjsunit.status
index b06fce2a9dee6aad21d81d9efe06d8d1e50915c1..9311c32b247b2afbbbbf3f13759315566ef8c91d 100644
--- a/test/mjsunit/mjsunit.status
+++ b/test/mjsunit/mjsunit.status
@@ -289,6 +289,10 @@
 
   # TODO(titzer): SSE 4.1 required for asm-wasm test (floor).
   'wasm/asm-wasm': [SKIP],
+
+    # case-insensitive unicode regexp relies on case mapping provided by ICU.
+  'harmony/unicode-regexp-ignore-case': [PASS, ['no_i18n == True', FAIL]],
+  'harmony/unicode-regexp-ignore-case-noi18n': [FAIL, ['no_i18n == True', PASS]],
 }],  # ALWAYS
 
 ['novfp3 == True', {