Add some support for the code-point code-unit distinction.

tests/language/language_dart2js.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.
 
 [ $compiler == dart2js || $compiler == dart2dart ]
 class_literal_test/01: Fail # Class literals are expression now; delete this test.
 class_literal_test/02: Fail # Class literals are expression now; delete this test.
 class_literal_test/05: Fail # Class literals are expression now; delete this test.
 class_literal_test/06: Fail # Class literals are expression now; delete this test.
 class_literal_test/07: Fail # Class literals are expression now; delete this test.
@@ skipping 133 matching lines @@
 
 # Fail "const EmptyLink<Element>" must be a compile-time constant if unchecked on linux.
 # Crash infinite loop on Mac and dart2js checked mode on linux.
 function_type_alias6_test: Crash, Fail
 
 
 # Compilation errors.
 const_var_test: Fail # Map literals take 2 type arguments.
 map_literal3_test: Fail # Map literals take 2 type arguments.
 ct_const_test: Fail # We don't take the generic type into account yet.
-char_escape_test: Fail # Unhandled non-BMP character: U+10000
 default_factory_library_test: Fail # lib is not a type
 dynamic_test: Fail # cannot resolve type F1
 constructor_redirect2_test/03: Fail # redirecting ctor with initializing formal
 factory3_test: Fail # internal error: visitIs for type variables not implemented
 function_type_alias2_test: Fail # cannot resolve type f1
 function_type_alias3_test: Fail # cannot resolve type F
 function_type_alias4_test: Fail # cannot resolve type F
 function_type_alias5_test/00: Fail # visitIs for typedefs not implemented
 function_type_alias5_test/01: Fail # visitIs for typedefs not implemented
 function_type_alias5_test/02: Fail # visitIs for typedefs not implemented
@@ skipping 207 matching lines @@
 [ $runtime == opera ]
 call_through_null_getter_test: Fail
 closure3_test: Fail
 execute_finally3_test: Fail
 method_invocation_test: Fail
 null_pointer_exception_test: Fail
 stack_overflow_test: Fail
 string_interpolate_npe_test: Fail
 closure_call_wrong_argument_count_negative_test: Skip
 label_test: Skip