Redo "Construct literal maps using factory constructor."

tests/utils/dummy_compiler_test.dart

Index: tests/utils/dummy_compiler_test.dart
diff --git a/tests/utils/dummy_compiler_test.dart b/tests/utils/dummy_compiler_test.dart
index 54742c79d3d801e0af3c1a80cd7c9b2845a8b109..f305e9cc8eb0d8c23373cf5bb41e371ce483003f 100644
--- a/tests/utils/dummy_compiler_test.dart
+++ b/tests/utils/dummy_compiler_test.dart
@@ -39,7 +39,10 @@ class BoundClosure {}
 class Dynamic_ {}
 class Null {}
 class StackTrace {}
-class LinkedHashMap {}
+class LinkedHashMap {
+  factory LinkedHashMap._empty() => null;
+  factory LinkedHashMap._literal(elements) => null;
+}
 identical(a, b) => true;
 getRuntimeTypeInfo(o) {}
 setRuntimeTypeInfo(o, i) {}