Fix issue 9939 by making the body of a try block have two successors: the join block after the try/…

tests/language/issue9939_test.dart

+// Copyright (c) 2013, 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.
+
+// dart2js was generating incorrect code for the [A] constructor, by
+// using a temporary variable for two instructions, even though they
+// are both live at the same time.
+
+import "package:expect/expect.dart";
+
+var globalVar = [1, 2];
+
+class A {
+  final field1;
+  final field2;
+  var field3;
+
+  A(this.field1, this.field2) {
+    bool entered = false;
+    // We use [field1] twice to ensure it will have a temporary.
+    for (var a in field1) {
+      try {
+        entered = true;
+        // We use [field2] twice to ensure it will have a temporary.
+        print(field2);
+        print(field2);
+      } catch (e) {
+        // Because the catch is aborting, the SSA graph we used to
+        // generate thought that the whole try/catch was aborting, and
+        // therefore it could not reach the code after the loop.
+        throw e;
+      }
+    }
+    Expect.isTrue(entered);
+    // dart2js used to overwrite the temporary for [field1] with
+    // [field2].
+    Expect.equals(globalVar, field1);
+  }
+}
+
+main() {
+  new A(globalVar, null);
+}