Add some more validation of things in expect that should not be used.

pkg/expect/lib/expect.dart

Index: pkg/expect/lib/expect.dart
diff --git a/pkg/expect/lib/expect.dart b/pkg/expect/lib/expect.dart
index 4d9c425275ad6c253b9ac5ac74320e05a505983f..c9810b03504f6398de48e8318643a343785c16f6 100644
--- a/pkg/expect/lib/expect.dart
+++ b/pkg/expect/lib/expect.dart
@@ -436,8 +436,7 @@ class Expect {
    *
    *     Expect.throws(myThrowingFunction, (e) => e is MyException);
    */
-  static void throws(void f(),
-      [_CheckExceptionFn check = null, String reason = null]) {
+  static void throws(void f(), [_CheckExceptionFn check, String reason]) {
     String msg = reason == null ? "" : "($reason)";
     if (f is! _Nullary) {
       // Only throws from executing the function body should count as throwing.
@@ -457,6 +456,35 @@ class Expect {
     _fail('Expect.throws$msg fails: Did not throw');
   }
 
+  static void throwsArgumentError(void f()) {
+    Expect.throws(f, (error) => error is ArgumentError, "ArgumentError");
+  }
+
+  static void throwsCastError(void f()) {
+    Expect.throws(f, (error) => error is CastError, "CastError");
+  }
+
+  static void throwsNoSuchMethodError(void f()) {
+    Expect.throws(
+        f, (error) => error is NoSuchMethodError, "NoSuchMethodError");
+  }
+
+  static void throwsRangeError(void f()) {
+    Expect.throws(f, (error) => error is RangeError, "RangeError");
+  }
+
+  static void throwsStateError(void f()) {
+    Expect.throws(f, (error) => error is StateError, "StateError");
+  }
+
+  static void throwsTypeError(void f()) {
+    Expect.throws(f, (error) => error is TypeError, "TypeError");
+  }
+
+  static void throwsUnsupportedError(void f()) {
+    Expect.throws(f, (error) => error is UnsupportedError, "UnsupportedError");
+  }
+
   static String _getMessage(String reason) =>
       (reason == null) ? "" : ", '$reason'";
 
@@ -505,6 +533,7 @@ class AssumeDynamic {
 }
 
 /// Is true iff type assertions are enabled.
+// TODO(rnystrom): Remove this once all tests are no longer using it.
 final bool typeAssertionsEnabled = (() {
   try {
     dynamic i = 42;
@@ -526,5 +555,6 @@ final bool assertStatementsEnabled = (() {
 })();
 
 /// Is true iff checked mode is enabled.
+// TODO(rnystrom): Remove this once all tests are no longer using it.
 final bool checkedModeEnabled =
     typeAssertionsEnabled && assertStatementsEnabled;