Change TypeInference to handle super calls as direct invocations.

This also makes calls of known target registered as static uses and thus
removes the need for misusing type masks to select super methods.

Closes dart-lang#25716

[email protected]

Committed: dart-lang@70159b7

Review URL: https://codereview.chromium.org/2423953002 .

Reverted: dart-lang@5397c54

Author: johnniwinther

pkg/compiler/lib/src/enqueue.dart

@@ -600,6 +600,10 @@ class ResolutionEnqueuer extends Enqueuer {
       case StaticUseKind.CONST_CONSTRUCTOR_INVOKE:
         registerTypeUse(new TypeUse.instantiation(staticUse.type));
         break;
+      case StaticUseKind.DIRECT_INVOKE:
+        invariant(
+            element, 'Direct static use is not supported for resolution.');
+        break;
     }
     if (addElement) {
       addToWorkList(element);

pkg/compiler/lib/src/inferrer/inferrer_visitor.dart

@@ -958,13 +958,6 @@ abstract class InferrerVisitor<T, E extends MinimalInferrerEngine<T>>
     }
   }
 
-  T _superType;
-  T get superType {
-    if (_superType != null) return _superType;
-    return _superType =
-        types.nonNullExact(outermostElement.enclosingClass.superclass);
-  }
-
   @override
   T visitThisGet(Identifier node, _) {
     return thisType;
@@ -974,7 +967,7 @@ abstract class InferrerVisitor<T, E extends MinimalInferrerEngine<T>>
     if (node.isThis()) {
       return thisType;
     } else if (node.isSuper()) {
-      return superType;
+      return internalError(node, 'Unexpected expression $node.');
     } else {
       Element element = elements[node];
       if (Elements.isLocal(element)) {