[cfe] Add test for type context in cascade

The question of whether type context was correctly passed through
cascade arose during debugging. Added a test to verify that
we handle it correctly.

Change-Id: Ic828296815f7e08af18d9cc8e0708dbc929a20f8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/155329
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>

Author: johnniwinther

pkg/front_end/testcases/general/cascade_context.dart

@@ -0,0 +1,15 @@
+// Copyright (c) 2020, 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.
+
+T f<T>() => null;
+
+test() {
+  int v1 = f();
+  int v2 = f()..isEven;
+  int v3 = f()
+    ..isEven
+    ..isEven;
+}
+
+main() {}

pkg/front_end/testcases/general/cascade_context.dart.outline.expect

@@ -0,0 +1,10 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+static method f<T extends core::Object* = dynamic>() → self::f::T*
+  ;
+static method test() → dynamic
+  ;
+static method main() → dynamic
+  ;

pkg/front_end/testcases/general/cascade_context.dart.strong.expect

@@ -0,0 +1,17 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+static method f<T extends core::Object* = dynamic>() → self::f::T*
+  return null;
+static method test() → dynamic {
+  core::int* v1 = self::f<core::int*>();
+  core::int* v2 = let final core::int* #t1 = self::f<core::int*>() in block {
+    #t1.{core::int::isEven};
+  } =>#t1;
+  core::int* v3 = let final core::int* #t2 = self::f<core::int*>() in block {
+    #t2.{core::int::isEven};
+    #t2.{core::int::isEven};
+  } =>#t2;
+}
+static method main() → dynamic {}

pkg/front_end/testcases/general/cascade_context.dart.strong.transformed.expect

@@ -0,0 +1,17 @@
+library;
+import self as self;
+import "dart:core" as core;
+
+static method f<T extends core::Object* = dynamic>() → self::f::T*
+  return null;
+static method test() → dynamic {
+  core::int* v1 = self::f<core::int*>();
+  core::int* v2 = let final core::int* #t1 = self::f<core::int*>() in block {
+    #t1.{core::int::isEven};
+  } =>#t1;
+  core::int* v3 = let final core::int* #t2 = self::f<core::int*>() in block {
+    #t2.{core::int::isEven};
+    #t2.{core::int::isEven};
+  } =>#t2;
+}
+static method main() → dynamic {}

pkg/front_end/testcases/general/cascade_context.dart.textual_outline.expect

@@ -0,0 +1,3 @@
+T f<T>() => null;
+test() {}
+main() {}

pkg/front_end/testcases/general/cascade_context.dart.textual_outline_modelled.expect

@@ -0,0 +1,3 @@
+T f<T>() => null;
+main() {}
+test() {}