dart2dart: Introduce compound assignment and prefix increment in dart_codegen.

tests/language/rewrite_compound_assign_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.
+
+import "package:expect/expect.dart";
+
+var global = 0;
+
+class Foo {
+    var field = 0;
+    static var staticField = 0;
+}
+
+field_compound1(obj) {
+    return obj.field = obj.field + 5;
+}
+field_compound2(obj) {
+    return obj.field = obj.field + 1;
+}
+field_compound3(obj) {
+    return obj.field = obj.field - 1;
+}
+field_compound4(obj) {
+    return obj.field = obj.field * 1;
+}
+
+static_compound1() {
+    return Foo.staticField = Foo.staticField + 5;
+}
+static_compound2() {
+    return Foo.staticField = Foo.staticField + 1;
+}
+static_compound3() {
+    return Foo.staticField = Foo.staticField - 1;
+}
+static_compound4() {
+    return Foo.staticField = Foo.staticField * 1;
+}
+
+global_compound1() {
+    return global = global + 5;
+}
+global_compound2() {
+    return global = global + 1;
+}
+global_compound3() {
+    return global = global - 1;
+}
+global_compound4() {
+    return global = global * 1;
+}
+
+local_compound1(x) {
+    x = x + 5;
+    if (x > 0) {
+        return x;
+    }
+    return -x;
+}
+local_compound2(x) {
+    x = x + 1;
+    if (x > 0) {
+        return x;
+    }
+    return -x;
+}
+local_compound3(x) {
+    x = x - 1;
+    if (x > 0) {
+        return x;
+    }
+    return -x;
+}
+local_compound4(x) {
+    x = x * 1;
+    if (x > 0) {
+        return x;
+    }
+    return -x;
+}
+
+main() {
+    var obj = new Foo();
+    Expect.equals(5, field_compound1(obj));
+    Expect.equals(5, obj.field);
+    Expect.equals(6, field_compound2(obj));
+    Expect.equals(6, obj.field);
+    Expect.equals(5, field_compound3(obj));
+    Expect.equals(5, obj.field);
+    Expect.equals(5, field_compound4(obj));
+    Expect.equals(5, obj.field);
+
+    Expect.equals(5, static_compound1());
+    Expect.equals(5, Foo.staticField);
+    Expect.equals(6, static_compound2());
+    Expect.equals(6, Foo.staticField);
+    Expect.equals(5, static_compound3());
+    Expect.equals(5, Foo.staticField);
+    Expect.equals(5, static_compound4());
+    Expect.equals(5, Foo.staticField);
+
+    Expect.equals(5, global_compound1());
+    Expect.equals(5, global);
+    Expect.equals(6, global_compound2());
+    Expect.equals(6, global);
+    Expect.equals(5, global_compound3());
+    Expect.equals(5, global);
+    Expect.equals(5, global_compound4());
+    Expect.equals(5, global);
+
+    Expect.equals(8, local_compound1(3));
+    Expect.equals(3, local_compound1(-8));
+    Expect.equals(4, local_compound2(3));
+    Expect.equals(7, local_compound2(-8));
+    Expect.equals(2, local_compound3(3));
+    Expect.equals(9, local_compound3(-8));
+    Expect.equals(3, local_compound4(3));
+    Expect.equals(8, local_compound4(-8));
+}