Expand ResolvedAst to handle synthetic constructors.

pkg/compiler/lib/src/serialization/element_serialization.dart

Index: pkg/compiler/lib/src/serialization/element_serialization.dart
diff --git a/pkg/compiler/lib/src/serialization/element_serialization.dart b/pkg/compiler/lib/src/serialization/element_serialization.dart
index 78228ca41395b8220d86395e999bb1b84fa97a54..b6991c021f38eb5defae934076bf8316c9c17d65 100644
--- a/pkg/compiler/lib/src/serialization/element_serialization.dart
+++ b/pkg/compiler/lib/src/serialization/element_serialization.dart
@@ -105,10 +105,11 @@ class SerializerUtil {
     if (element.sourcePosition != null) {
       SourceSpan position = element.sourcePosition;
       encoder.setInt(Key.OFFSET, position.begin);
-      if (position.uri != element.compilationUnit.script.resourceUri) {
-        // TODO(johnniwinther): What is the base URI in the case?
-        encoder.setUri(Key.URI, element.library.canonicalUri, position.uri);
-      }
+      // TODO(johnniwinther): Figure out why the omitted the uri if
+      // `position.uri != element.compilationUnit.script.resourceUri` does not
+      // always work, for instance for LinkedHashMap#_literal.
+      // TODO(johnniwinther): What is the base URI in the case?
+      encoder.setUri(Key.URI, element.library.canonicalUri, position.uri);
       int length = position.end - position.begin;
       if (element.name.length != length) {
         encoder.setInt(Key.LENGTH, length);