Start implementing checked mode and tools support for using it.

tests/language/language.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.
 
 # This directory contains tests that are intended to show the
 # current state of the language.
 
 # In order to maintain maximum test coverage for all builds,
 # please use the following procedure to mark a test
 # failed on architectures other than the one you are working on.
@@ skipping 436 matching lines @@
 [ $compiler == frog && $runtime == none ]
 *: Skip
 
 [ $arch == simarm ]
 *: Skip
 
 [ $arch == arm ]
 *: Skip
 
 [ $compiler == dart2js && $checked ]
-*: Skip
+assign_static_type_test/01: Fail
+assign_static_type_test/02: Fail
+assign_static_type_test/03: Fail
+assign_static_type_test/04: Fail
+assign_static_type_test/05: Fail
+type_variable_bounds_test/01: Fail
+type_variable_bounds_test/02: Fail
+type_variable_bounds_test/04: Fail
+type_variable_bounds_test/05: Fail
+type_variable_bounds2_test/00: Fail
+type_variable_bounds2_test/02: Pass # For the wrong reasons.
+type_variable_bounds2_test/03: Fail
+type_variable_bounds2_test/05: Fail
+type_variable_bounds2_test/06: Pass # For the wrong reasons.
+assign_top_method_negative_test: Pass # For the wrong reasons.
 
 
 [ $compiler == dart2js]
 compile_time_constant8_test: Fail # We don't take the generic type into account yet.
 static_initializer_type_error_test: Fail # Checked mode not supported.
 
 
 # Compilation errors.
 ct_const_test: Fail # We don't take the generic type into account yet.
 call_operator_test: Fail # Unexpected token 'call'
@@ skipping 189 matching lines @@
 
 list_test: Fail, OK # Obsolete test uses List.copyFrom that was removed on 2011-10-31.
 
 final_syntax_test/none: Fail, OK # Uses deprecated "StrConstant + StrConstant".
 
 [ $compiler == dart2js && $mode == release ]
 assign_top_method_negative_test: Crash
 
 [ $compiler == dart2js && $runtime == none ]
 *: Fail, Pass # TODO(ahe): Triage these tests.