Bubble up exceptions throw async/await.

tests/language/await_exceptions_test.dart

+// Copyright (c) 2014, 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.
+
+// VMOptions=--enable_async --optimization-counter-threshold=5
+
+import 'package:expect/expect.dart';
+
+import 'dart:async';
+
+// It does not matter where a future is generated.
+bar(p) async => p;
+baz(p) => new Future(() => p);
+
+test0_1() async {
+  throw 1;
+}
+
+test0() async {
+  try {
+    await test0_1();
+  } catch (e) {
+    Expect.equals(1, e);
+  }
+}
+
+test1_1() async {
+  throw 1;
+}
+
+test1_2() async {
+  try {
+    await test1_1();
+  } catch (e) {
+    throw e+1;
+  }
+}
+
+test1() async {
+  try {
+    await test1_2();
+  } catch (e) {
+    Expect.equals(2, e);
+  }
+}
+
+test2() async {
+  var x;
+  var test2_1 = () async {
+    try {
+      throw 'a';
+    } catch (e) {
+      throw e + 'b';
+    }
+  };
+  try {
+    try {
+      await test2_1();
+    } catch (e) {
+      var y = await bar(e + 'c');
+      throw y;
+    }
+  } catch (e) {
+    x = e + 'd';
+    return '?';
+  } finally {
+    return x;
+  }
+  return '!';
+}
+
+main() async {
+  var result;
+  for (int i = 0; i < 10; i++) {
+    await test0();
+    await test1();
+    result = await test2();
+    Expect.equals('abcd', result);
+  }
+}