Update expectations files to get more strong mode inference tests to pass.

pkg/front_end/testcases/inference/propagate_inference_transitively2.dart.strong.expect

+library test;
+import self as self;
+import "dart:core" as core;
+
+class A extends core::Object {
+  field core::int x = 42;
+  constructor •() → void
+    : super core::Object::•()
+    ;
+}
+class B extends core::Object {
+  field self::A a = new self::A::•();
+  constructor •() → void
+    : super core::Object::•()
+    ;
+}
+class C extends core::Object {
+  field self::B b = new self::B::•();
+  constructor •() → void
+    : super core::Object::•()
+    ;
+}
+class D extends core::Object {
+  field self::C c = new self::C::•();
+  constructor •() → void
+    : super core::Object::•()
+    ;
+}
+static method main() → void {
+  self::D d1 = new self::D::•();
+  core::print(d1.c.b.a.x);
+  self::D d2 = new self::D::•();
+  core::print(d2.c.b.a.x);
+}