Downwards inference. This adds support to the resolver for downwards

pkg/analyzer/lib/src/task/strong/rules.dart

Index: pkg/analyzer/lib/src/task/strong/rules.dart
diff --git a/pkg/analyzer/lib/src/task/strong/rules.dart b/pkg/analyzer/lib/src/task/strong/rules.dart
index 32236a8aaee630c3d0584190def357676a92d62e..6503c22cdac75484430ffdea653a371f5f211a08 100644
--- a/pkg/analyzer/lib/src/task/strong/rules.dart
+++ b/pkg/analyzer/lib/src/task/strong/rules.dart
@@ -421,6 +421,7 @@ class TypeRules {
     var reason = null;
 
     var errors = <String>[];
+    
     var ok = inferrer.inferExpression(expr, toT, errors);
     if (ok) return InferredType.create(this, expr, toT);
     reason = (errors.isNotEmpty) ? errors.first : null;
@@ -508,24 +509,11 @@ class DownwardsInference {
   /// Downward inference
   bool _inferExpression(Expression e, DartType t, List<String> errors,
       {cast: true}) {
-    if (e is ConditionalExpression) {
-      return _inferConditionalExpression(e, t, errors);
-    }
-    if (e is ParenthesizedExpression) {
-      return _inferParenthesizedExpression(e, t, errors);
-    }
     if (rules.isSubTypeOf(rules.getStaticType(e), t)) return true;
     if (cast && rules.getStaticType(e).isDynamic) {
       annotateCastFromDynamic(e, t);
       return true;
     }
-    if (e is FunctionExpression) return _inferFunctionExpression(e, t, errors);
-    if (e is ListLiteral) return _inferListLiteral(e, t, errors);
-    if (e is MapLiteral) return _inferMapLiteral(e, t, errors);
-    if (e is NamedExpression) return _inferNamedExpression(e, t, errors);
-    if (e is InstanceCreationExpression) {
-      return _inferInstanceCreationExpression(e, t, errors);
-    }
     errors.add("$e cannot be typed as $t");
     return false;
   }