Fix "extends" checks. Move them out of resolve phase and do them on demand.

tests/language/language.status

 # Copyright (c) 2011, 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 290 matching lines @@
 PseudoKWNegativeTest: Fail # verifying test vs. spec - issue #356
 RegExp3Test: Fail
 ScopeNegativeTest: Fail
 ScriptNegativeTest: Fail
 StringEscapesTest: Fail
 StringTest: Fail
 SuperImplicitClosureTest: Fail
 SuperTest: Fail  # this is testing precise ordering of super constructor call
 SwitchLabelTest: Fail
 TryCatch9NegativeTest: Fail
-TypeVariableBoundsTest/none: Fail # Issue 417
-TypeVariableBoundsTest/00: Fail # Issue 417
-TypeVariableBoundsTest/03: Fail # Issue 417
-TypeVariableBoundsTest/04: Fail # Issue 417
-TypeVariableScopeTest/00: Fail # These negative tests were passing incorrectly
+TypeVariableBoundsTest/01: Fail # these tests would work if the type was constructed
+TypeVariableBoundsTest/02: Fail
+TypeVariableBoundsTest/05: Fail
+TypeVariableBoundsTest/06: Fail
+TypeVariableScopeTest/00: Fail
 TypeVariableScopeTest/02: Fail
 TypeVariableScopeTest/03: Fail
 TypeVariableScopeTest/04: Fail
 TypeVariableScopeTest/06: Fail
 WrongNumberTypeArgumentsTest: Fail
 ImplicitThisTest/01: Fail # Issue 376
 ImplicitThisTest/02: Fail # Issue 376
 ImplicitThisTest/03: Fail # Issue 376
 ImplicitThisTest/04: Fail # Issue 376
 ImplicitThisTest/none: Fail # Issue 376
@@ skipping 48 matching lines @@
 StaticField2RunNegativeTest: Fail
 
 [ $arch == x64 ]
 *: Skip
 
 [ $arch == simarm ]
 *: Skip
 
 [ $arch == arm ]
 *: Skip