Handle assert with message in type inference

tests/compiler/dart2js/assert_message_throw_test.dart

Index: tests/compiler/dart2js/assert_message_throw_test.dart
diff --git a/tests/compiler/dart2js/assert_message_throw_test.dart b/tests/compiler/dart2js/assert_message_throw_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..75a5bb4571267faa686288348c5b18720bb3f5d4
--- /dev/null
+++ b/tests/compiler/dart2js/assert_message_throw_test.dart
@@ -0,0 +1,76 @@
+// Copyright (c) 2016, 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:async_helper/async_helper.dart';
+import 'package:compiler/src/commandline_options.dart';
+import 'package:compiler/src/compiler.dart';
+import 'package:compiler/src/elements/elements.dart';
+import 'package:compiler/src/types/masks.dart';
+import 'package:expect/expect.dart';
+import 'memory_compiler.dart';
+import 'type_mask_test_helper.dart';
+
+const String SOURCE = '''
+main(args) {
+  test0();
+  test1(args == null);
+  test2(args == null);
+  test3(args);
+}
+
+// Check that `throw` in the message does is handled conditionally.
+test0() {
+  assert(true, throw "unreachable");
+  var list = [];
+  return list;
+}
+
+// Check that side-effects of the assert message is not included after the
+// assert.
+test1(b) {
+  var a;
+  assert(b, a = 42);
+  return a;
+}
+
+// Check that side-effects of the assert message is included after the assert
+// through the thrown exception.
+test2(b) {
+  var a;
+  try {
+    assert(b, a = 42);
+  } catch (e) {}
+  return a;
+}
+
+// Check that type tests are preserved after the assert.
+test3(a) {
+  assert(a is int);
+  return a;
+}
+''';
+
+main() {
+  asyncTest(() async {
+    CompilationResult result = await runCompiler(
+        entryPoint: Uri.parse('memory:main.dart'),
+        memorySourceFiles: {'main.dart': SOURCE},
+        options: [Flags.enableCheckedMode, Flags.enableAssertMessage]);
+    Compiler compiler = result.compiler;
+
+    void check(String methodName, TypeMask expectedReturnType) {
+      Element element = compiler.mainApp.find(methodName);
+      TypeMask typeMask = simplify(
+          compiler.globalInference.results.resultOf(element).returnType,
+          compiler);
+      Expect.equals(expectedReturnType, typeMask,
+          "Unexpected return type on method '$methodName'.");
+    }
+
+    check('test0', compiler.closedWorld.commonMasks.growableListType);
+    check('test1', compiler.closedWorld.commonMasks.nullType);
+    check('test2', compiler.closedWorld.commonMasks.uint31Type.nullable());
+    check('test3', compiler.closedWorld.commonMasks.intType);
+  });
+}