Fix issue 10487 by adapting the type checker so it uses the dynamic type for throw expressions.

tests/language/throw_expr_test.dart

 // 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.
 
 import "package:expect/expect.dart";
 
 // Dart test program for testing throw expressions.
 
 void test1() {
   var x = 6;
@@ skipping 30 matching lines @@
   Expect.equals(15, x);
 }
 
 foo(x, y) => throw "foo" "$x";
 
 bar(x, y) => throw "foo" "${throw x}";
 
 class Q {
   var qqq;
   f(x) { qqq = x; }
+  Q get nono => throw "nono";
 }
 
 void test3() {
   try {
     throw throw throw "up";
   } catch(e) {
     Expect.equals("up", e);
   }
 
   var x = 10;
@@ skipping 23 matching lines @@
   x = null;
   try {
     x = new Q();
     x..f(11) ..qqq = throw 77 ..f(22);
   } catch(e) {
     Expect.equals(77, e);
     Expect.equals(11, x.qqq);
   }
 }
 
+void test4() {
+  var q = new Q();
+  Expect.throws(() => q.nono, (e) => e == "nono");
+}
+
 main() {
   test1();
   test2();
   test3();
+  test4();
 }