fix #25487, infer block lambdas from return statements

pkg/analyzer/test/src/task/strong/inferred_type_test.dart

Index: pkg/analyzer/test/src/task/strong/inferred_type_test.dart
diff --git a/pkg/analyzer/test/src/task/strong/inferred_type_test.dart b/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
index 85a1085bef0fc6b253a86b6854b5c9315a60e496..f63285281e4ceb9e4a561b26a20c01de046f0d7d 100644
--- a/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
+++ b/pkg/analyzer/test/src/task/strong/inferred_type_test.dart
@@ -1919,4 +1919,29 @@ test2() {
 }
     ''');
   });
+
+
+  test('block bodied lambdas', () {
+    // Regression test for https://github.com/dart-lang/sdk/issues/25487
+    checkFile(r'''
+import 'dart:math' show Random;
+test1() {
+  List<int> o;
+  var y = o.map(/*info:INFERRED_TYPE_CLOSURE,info:INFERRED_TYPE_CLOSURE*/(x) { return x + 1; });
+  Iterable<int> z = y;
+}
+test2() {
+  List<num> o;
+  var y = o.map(/*info:INFERRED_TYPE_CLOSURE,info:INFERRED_TYPE_CLOSURE*/(x) {
+    if (new Random().nextBool()) {
+      return x.toInt() + 1;
+    } else {
+      return x.toDouble();
+    }
+  });
+  Iterable<num> w = y;
+  Iterable<int> z = /*info:ASSIGNMENT_CAST*/y;
+}

[Leaf, 2016/02/23 02:17:47]

I'd like to be sure we cover this pretty well.  Can you please add tests for:

1) Inferred type is top
2) Inferred type is bottom
3) return null;
4) async functions, returning:
  a) All futures
  b) All values
  c) Futures and values
5) A sync* and async* example
6) An example where the downwards inference type is incompatible with the
upwards inference type.
7) Nested lambdas.

[Jennifer Messerly, 2016/02/23 17:41:46]

Excellent list. Yeah I can do that.

[Jennifer Messerly, 2016/02/24 00:20:41]

Done.

+    ''');
+  });
 }