Add type inference for assignments to `this[...]`

pkg/front_end/testcases/inference/infer_assign_to_index_this_upwards.dart

Index: pkg/front_end/testcases/inference/infer_assign_to_index_this_upwards.dart
diff --git a/pkg/front_end/testcases/inference/infer_assign_to_index_this_upwards.dart b/pkg/front_end/testcases/inference/infer_assign_to_index_this_upwards.dart
new file mode 100644
index 0000000000000000000000000000000000000000..a71cf809107a851f869ed4c07425120e53911a3a
--- /dev/null
+++ b/pkg/front_end/testcases/inference/infer_assign_to_index_this_upwards.dart
@@ -0,0 +1,168 @@
+// Copyright (c) 2017, 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.
+
+/*@testedFeatures=inference*/
+library test;
+
+int getInt() => 0;
+num getNum() => 0;
+double getDouble() => 0.0;
+
+abstract class Test1 {
+  int operator [](String s);
+  void operator []=(String s, int v);
+
+  void test() {
+    var /*@type=int*/ v1 = this /*@target=Test1::[]=*/ ['x'] = getInt();
+    var /*@type=num*/ v2 = this /*@target=Test1::[]=*/ ['x'] = getNum();
+    var /*@type=int*/ v4 = this /*@target=Test1::[]=*/ ['x'] ??= getInt();
+    var /*@type=num*/ v5 = this /*@target=Test1::[]=*/ ['x'] ??= getNum();
+    var /*@type=int*/ v7 = this /*@target=Test1::[]=*/ ['x'] += getInt();
+    var /*@type=num*/ v8 = this /*@target=Test1::[]=*/ ['x'] += getNum();
+    var /*@type=int*/ v10 = ++this /*@target=Test1::[]=*/ ['x'];
+    var /*@type=int*/ v11 = this /*@target=Test1::[]=*/ ['x']++;
+  }
+}
+
+abstract class Test2 {
+  int operator [](String s);
+  void operator []=(String s, num v);
+
+  void test() {
+    var /*@type=int*/ v1 = this /*@target=Test2::[]=*/ ['x'] = getInt();
+    var /*@type=num*/ v2 = this /*@target=Test2::[]=*/ ['x'] = getNum();
+    var /*@type=double*/ v3 = this /*@target=Test2::[]=*/ ['x'] = getDouble();
+    var /*@type=num*/ v4 = this /*@target=Test2::[]=*/ ['x'] ??= getInt();
+    var /*@type=num*/ v5 = this /*@target=Test2::[]=*/ ['x'] ??= getNum();
+    var /*@type=num*/ v6 = this /*@target=Test2::[]=*/ ['x'] ??= getDouble();
+    var /*@type=num*/ v7 = this /*@target=Test2::[]=*/ ['x'] += getInt();
+    var /*@type=num*/ v8 = this /*@target=Test2::[]=*/ ['x'] += getNum();
+    var /*@type=num*/ v9 = this /*@target=Test2::[]=*/ ['x'] += getDouble();
+    var /*@type=num*/ v10 = ++this /*@target=Test2::[]=*/ ['x'];
+    var /*@type=num*/ v11 = this /*@target=Test2::[]=*/ ['x']++;
+  }
+}
+
+abstract class Test3 {
+  int operator [](String s);
+  void operator []=(String s, double v);
+
+  void test() {
+    var /*@type=num*/ v2 = this /*@target=Test3::[]=*/ ['x'] = getNum();
+    var /*@type=double*/ v3 = this /*@target=Test3::[]=*/ ['x'] = getDouble();
+    var /*@type=num*/ v5 = this /*@target=Test3::[]=*/ ['x'] ??= getNum();
+    var /*@type=double*/ v6 = this /*@target=Test3::[]=*/ ['x'] ??= getDouble();
+    var /*@type=double*/ v7 = this /*@target=Test3::[]=*/ ['x'] += getInt();
+    var /*@type=double*/ v8 = this /*@target=Test3::[]=*/ ['x'] += getNum();
+    var /*@type=double*/ v9 = this /*@target=Test3::[]=*/ ['x'] += getDouble();
+    var /*@type=double*/ v10 = ++this /*@target=Test3::[]=*/ ['x'];
+    var /*@type=double*/ v11 = this /*@target=Test3::[]=*/ ['x']++;
+  }
+}
+
+abstract class Test4 {
+  num operator [](String s);
+  void operator []=(String s, int v);
+
+  void test() {
+    var /*@type=int*/ v1 = this /*@target=Test4::[]=*/ ['x'] = getInt();
+    var /*@type=num*/ v2 = this /*@target=Test4::[]=*/ ['x'] = getNum();
+    var /*@type=int*/ v4 = this /*@target=Test4::[]=*/ ['x'] ??= getInt();
+    var /*@type=num*/ v5 = this /*@target=Test4::[]=*/ ['x'] ??= getNum();
+    var /*@type=int*/ v7 = this /*@target=Test4::[]=*/ ['x'] += getInt();
+    var /*@type=num*/ v8 = this /*@target=Test4::[]=*/ ['x'] += getNum();
+    var /*@type=int*/ v10 = ++this /*@target=Test4::[]=*/ ['x'];
+    var /*@type=int*/ v11 = this /*@target=Test4::[]=*/ ['x']++;
+  }
+}
+
+abstract class Test5 {
+  num operator [](String s);
+  void operator []=(String s, num v);
+
+  void test() {
+    var /*@type=int*/ v1 = this /*@target=Test5::[]=*/ ['x'] = getInt();
+    var /*@type=num*/ v2 = this /*@target=Test5::[]=*/ ['x'] = getNum();
+    var /*@type=double*/ v3 = this /*@target=Test5::[]=*/ ['x'] = getDouble();
+    var /*@type=num*/ v4 = this /*@target=Test5::[]=*/ ['x'] ??= getInt();
+    var /*@type=num*/ v5 = this /*@target=Test5::[]=*/ ['x'] ??= getNum();
+    var /*@type=num*/ v6 = this /*@target=Test5::[]=*/ ['x'] ??= getDouble();
+    var /*@type=num*/ v7 = this /*@target=Test5::[]=*/ ['x'] += getInt();
+    var /*@type=num*/ v8 = this /*@target=Test5::[]=*/ ['x'] += getNum();
+    var /*@type=num*/ v9 = this /*@target=Test5::[]=*/ ['x'] += getDouble();
+    var /*@type=num*/ v10 = ++this /*@target=Test5::[]=*/ ['x'];
+    var /*@type=num*/ v11 = this /*@target=Test5::[]=*/ ['x']++;
+  }
+}
+
+abstract class Test6 {
+  num operator [](String s);
+  void operator []=(String s, double v);
+
+  void test() {
+    var /*@type=num*/ v2 = this /*@target=Test6::[]=*/ ['x'] = getNum();
+    var /*@type=double*/ v3 = this /*@target=Test6::[]=*/ ['x'] = getDouble();
+    var /*@type=num*/ v5 = this /*@target=Test6::[]=*/ ['x'] ??= getNum();
+    var /*@type=double*/ v6 = this /*@target=Test6::[]=*/ ['x'] ??= getDouble();
+    var /*@type=double*/ v7 = this /*@target=Test6::[]=*/ ['x'] += getInt();
+    var /*@type=double*/ v8 = this /*@target=Test6::[]=*/ ['x'] += getNum();
+    var /*@type=double*/ v9 = this /*@target=Test6::[]=*/ ['x'] += getDouble();
+    var /*@type=double*/ v10 = ++this /*@target=Test6::[]=*/ ['x'];
+    var /*@type=double*/ v11 = this /*@target=Test6::[]=*/ ['x']++;
+  }
+}
+
+abstract class Test7 {
+  double operator [](String s);
+  void operator []=(String s, int v);
+
+  void test() {
+    var /*@type=int*/ v1 = this /*@target=Test7::[]=*/ ['x'] = getInt();
+    var /*@type=num*/ v2 = this /*@target=Test7::[]=*/ ['x'] = getNum();
+    var /*@type=int*/ v4 = this /*@target=Test7::[]=*/ ['x'] ??= getInt();
+    var /*@type=num*/ v5 = this /*@target=Test7::[]=*/ ['x'] ??= getNum();
+    var /*@type=int*/ v7 = this /*@target=Test7::[]=*/ ['x'] += getInt();
+    var /*@type=num*/ v8 = this /*@target=Test7::[]=*/ ['x'] += getNum();
+    var /*@type=int*/ v10 = ++this /*@target=Test7::[]=*/ ['x'];
+    var /*@type=int*/ v11 = this /*@target=Test7::[]=*/ ['x']++;
+  }
+}
+
+abstract class Test8 {
+  double operator [](String s);
+  void operator []=(String s, num v);
+
+  void test() {
+    var /*@type=int*/ v1 = this /*@target=Test8::[]=*/ ['x'] = getInt();
+    var /*@type=num*/ v2 = this /*@target=Test8::[]=*/ ['x'] = getNum();
+    var /*@type=double*/ v3 = this /*@target=Test8::[]=*/ ['x'] = getDouble();
+    var /*@type=num*/ v4 = this /*@target=Test8::[]=*/ ['x'] ??= getInt();
+    var /*@type=num*/ v5 = this /*@target=Test8::[]=*/ ['x'] ??= getNum();
+    var /*@type=num*/ v6 = this /*@target=Test8::[]=*/ ['x'] ??= getDouble();
+    var /*@type=num*/ v7 = this /*@target=Test8::[]=*/ ['x'] += getInt();
+    var /*@type=num*/ v8 = this /*@target=Test8::[]=*/ ['x'] += getNum();
+    var /*@type=num*/ v9 = this /*@target=Test8::[]=*/ ['x'] += getDouble();
+    var /*@type=num*/ v10 = ++this /*@target=Test8::[]=*/ ['x'];
+    var /*@type=num*/ v11 = this /*@target=Test8::[]=*/ ['x']++;
+  }
+}
+
+abstract class Test9 {
+  double operator [](String s);
+  void operator []=(String s, double v);
+
+  void test() {
+    var /*@type=num*/ v2 = this /*@target=Test9::[]=*/ ['x'] = getNum();
+    var /*@type=double*/ v3 = this /*@target=Test9::[]=*/ ['x'] = getDouble();
+    var /*@type=num*/ v5 = this /*@target=Test9::[]=*/ ['x'] ??= getNum();
+    var /*@type=double*/ v6 = this /*@target=Test9::[]=*/ ['x'] ??= getDouble();
+    var /*@type=double*/ v7 = this /*@target=Test9::[]=*/ ['x'] += getInt();
+    var /*@type=double*/ v8 = this /*@target=Test9::[]=*/ ['x'] += getNum();
+    var /*@type=double*/ v9 = this /*@target=Test9::[]=*/ ['x'] += getDouble();
+    var /*@type=double*/ v10 = ++this /*@target=Test9::[]=*/ ['x'];
+    var /*@type=double*/ v11 = this /*@target=Test9::[]=*/ ['x']++;
+  }
+}
+
+main() {}