Implement type inference for PropertyGet.

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

Index: pkg/front_end/testcases/inference/propagate_inference_to_field_in_class.dart.strong.expect
diff --git a/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class.dart.strong.expect b/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class.dart.strong.expect
new file mode 100644
index 0000000000000000000000000000000000000000..2ffa41cad7c3f0d371f0b9ca322c7b7c475b11df
--- /dev/null
+++ b/pkg/front_end/testcases/inference/propagate_inference_to_field_in_class.dart.strong.expect
@@ -0,0 +1,16 @@
+library test;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  field core::int x = 2;
+  constructor •() → void
+    : super core::Object::•()
+    ;
+}
+static method main() → dynamic {
+  self::A a = new self::A::•();
+  self::A b = a;
+  core::print(a.{self::A::x});
+  core::print(a.{self::A::x}.{core::num::+}(2));
+}