Add type inference logic for map literals

pkg/front_end/testcases/inference/unsafe_block_closure_inference_in_map_untyped.dart.strong.expect

Index: pkg/front_end/testcases/inference/unsafe_block_closure_inference_in_map_untyped.dart.strong.expect
diff --git a/pkg/front_end/testcases/inference/unsafe_block_closure_inference_in_map_untyped.dart.strong.expect b/pkg/front_end/testcases/inference/unsafe_block_closure_inference_in_map_untyped.dart.strong.expect
new file mode 100644
index 0000000000000000000000000000000000000000..20d29e832c271b08ede0d1217a68923f770b8533
--- /dev/null
+++ b/pkg/front_end/testcases/inference/unsafe_block_closure_inference_in_map_untyped.dart.strong.expect
@@ -0,0 +1,9 @@
+library test;
+import self as self;
+import "dart:core" as core;
+
+static method main() → dynamic {
+  core::Map<core::int, () → core::int> v = <core::int, () → core::int>{1: () → core::int {
+    return 1;
+  }};
+}