Handle `new Object()` in compile_from_dill_test

pkg/compiler/lib/src/common_elements.dart

Index: pkg/compiler/lib/src/common_elements.dart
diff --git a/pkg/compiler/lib/src/common_elements.dart b/pkg/compiler/lib/src/common_elements.dart
index 7ec4c139ae4cdba56908fbb5e2c20eaf80c24ade..47cfb9387c3cdf76d1cc1e78c1389289e962083c 100644
--- a/pkg/compiler/lib/src/common_elements.dart
+++ b/pkg/compiler/lib/src/common_elements.dart
@@ -1171,6 +1171,9 @@ abstract class ElementEnvironment {
   /// Returns all known libraries.
   Iterable<LibraryEntity> get libraries;
 
+  /// Returns the library name of [library] or '' if the library is unnamed.
+  String getLibraryName(LibraryEntity library);
+
   /// Lookup the library with the canonical [uri], fail if the library is
   /// missing and [required];
   LibraryEntity lookupLibrary(Uri uri, {bool required: false});