Migrate language/arithmetic2_test ... language/async_await_syntax_test.

tests/language_2/assignable_expression_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.
+
+// Test to detect syntactically illegal left-hand-side (assignable)
+// expressions.
+
+class C {
+  static dynamic field = 0;
+}
+
+dynamic variable = 0;
+
+main() {
+  variable = 0;
+  (variable) = 0; //   //# 01: compile-time error
+  (variable)++; //     //# 02: compile-time error
+  ++(variable); //     //# 03: compile-time error
+
+  C.field = 0;
+  (C.field) = 0; //  //# 11: compile-time error
+  (C.field)++; //    //# 12: compile-time error
+  ++(C.field); //    //# 13: compile-time error
+
+  variable = [1, 2, 3];
+  variable[0] = 0;
+  (variable)[0] = 0;
+  (variable[0]) = 0; //   //# 21: compile-time error
+  (variable[0])++; //     //# 22: compile-time error
+  ++(variable[0]); //     //# 23: compile-time error
+
+  C.field = [1, 2, 3];
+  (C.field[0]) = 0; //  //# 31: compile-time error
+  (C.field[0])++; //    //# 32: compile-time error
+  ++(C.field[0]); //    //# 33: compile-time error
+
+  var a = 0;
+  (a) = 0; //  //# 41: compile-time error
+  (a)++; //    //# 42: compile-time error
+  ++(a); //    //# 43: compile-time error
+
+  // Neat palindrome expression. x is assignable, ((x)) is not.
+  var funcnuf = (x) => ((x))=((x)) <= (x); // //# 50: compile-time error
+}