Make RegExp constructor non-const.

tests/co19/co19-runtime.status

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 # These tests either wrongly expect a compile-time error or wrongly reject a type error in production mode, co19 issue 282:
 [ $compiler == none && $runtime == vm ]
 Language/13_Libraries_and_Scripts/1_Imports_A03_t05: Fail, OK
 Language/13_Libraries_and_Scripts/1_Imports_A03_t08: Fail, OK
 Language/13_Libraries_and_Scripts/1_Imports_A03_t25: Fail, OK
 Language/13_Libraries_and_Scripts/1_Imports_A03_t28: Fail, OK
@@ skipping 346 matching lines @@
 LibTest/core/RegExp/firstMatch_A01_t01: Fail, OK # co19 issue 294
 LibTest/core/RegExp/Pattern_semantics/firstMatch_Atom_A02_t01: Fail, OK # co19 issue 294
 LibTest/core/RegExp/Pattern_semantics/firstMatch_Term_A03_t01: Fail, OK # co19 issue 294
 
 LibTest/core/Queue/first_A02_t01: Fail, OK # co19 issue 291
 LibTest/core/Queue/last_A02_t01: Fail, OK # co19 issue 291
 
 Language/11_Expressions/07_Maps_A07_t03: Fail, OK # co19 issue 287
 Language/11_Expressions/07_Maps_A04_t02: Fail, OK # co19 issue 287
 
+LibTest/core/RegExp/RegExp_A01_t04: Fail, OK # co19 issue 314
+LibTest/core/String/contains_A01_t01: Fail, OK # co19 issue 314
+
 LibTest/core/Map/getValues_A01_t02: Fail, OK # co19 issue 287
 
 [ $compiler == none && $runtime == vm ]
 LibTest/core/String/contains_A01_t03: Skip # Times out.
 
 LibTest/core/String/contains_A01_t02: Fail
 
 
 [ $compiler == none && $runtime == vm && $arch == ia32 ]
 LibTest/core/int/operator_left_shift_A01_t02: Fail # co19 issue 129
@@ skipping 40 matching lines @@
 
 
 [ $compiler == none && $runtime == vm && $mode == debug ]
 LibTest/isolate/isolate_api/spawnFunction_A02_t01: Crash
 
 [ $compiler == none && $arch == simarm ]
 *: Skip
 
 [ $compiler == none && $arch == arm ]
 *: Skip