Support serialization of all resolved asts from dart:core

pkg/compiler/lib/src/js_backend/backend_helpers.dart

Index: pkg/compiler/lib/src/js_backend/backend_helpers.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend_helpers.dart b/pkg/compiler/lib/src/js_backend/backend_helpers.dart
index aac308d4c2f5f19dd10a04bac14a6a36f915752f..7013def330b6e0450445163e71d394ca2f335552 100644
--- a/pkg/compiler/lib/src/js_backend/backend_helpers.dart
+++ b/pkg/compiler/lib/src/js_backend/backend_helpers.dart
@@ -18,8 +18,11 @@ import '../elements/elements.dart'
         EnumClassElement,
         FunctionElement,
         LibraryElement,
-        MethodElement;
+        MethodElement,
+        PublicName;
 import '../library_loader.dart' show LoadedLibraries;
+import '../universe/call_structure.dart' show CallStructure;
+import '../universe/selector.dart' show Selector;
 
 import 'js_backend.dart';
 
@@ -174,6 +177,32 @@ class BackendHelpers {
   /// Holds the class for the [JsBuiltins] enum.
   EnumClassElement jsBuiltinEnum;
 
+  ClassElement _symbolImplementationClass;
+  ClassElement get symbolImplementationClass {

[Siggi Cherem (dart-lang), 2016/04/14 15:38:20]

nit - rewrite as:

ClassElement get symbolImplementationClass =>
    _symbolImplementationClass ??= find(internalLibrary, 'Symbol');

[Johnni Winther, 2016/04/15 07:27:42]

Done.

+    if (_symbolImplementationClass == null) {
+      _symbolImplementationClass = find(internalLibrary, 'Symbol');
+    }
+    return _symbolImplementationClass;
+  }
+
+  final Selector symbolValidatedConstructorSelector =
+      new Selector.call(const PublicName('validated'), CallStructure.ONE_ARG);
+
+  ConstructorElement _symbolValidatedConstructor;
+  ConstructorElement get symbolValidatedConstructor {
+    if (_symbolValidatedConstructor == null) {
+      String name = symbolValidatedConstructorSelector.name;

[Siggi Cherem (dart-lang), 2016/04/14 15:38:20]

Maybe introduce a helper method for these lookups?  (I'm guessing this pattern
to lookup a constructor/member is going to come up several times and is similar
to the one in compiler.dart already.). For example:

ConstructorElement get symbolValidatedConstructor =>
    _symbolValidatedConstructor ??= findConstructor(symbolImplementationClass,
'validated')

[Johnni Winther, 2016/04/15 07:27:42]

Done.

+      symbolImplementationClass.ensureResolved(resolution);
+      _symbolValidatedConstructor =
+          symbolImplementationClass.lookupConstructor(name);
+      assert(invariant(
+          symbolImplementationClass, _symbolValidatedConstructor != null,
+          message: "Constructor '$name' not found in "
+              "'${symbolImplementationClass}'."));
+    }
+    return _symbolValidatedConstructor;
+  }
+
   // TODO(johnniwinther): Make these private.
   // TODO(johnniwinther): Split into findHelperFunction and findHelperClass and
   // add a check that the element has the expected kind.