Fix crash in compiler in the presence of "new library_prefix()".

sdk/lib/_internal/compiler/implementation/resolution/members.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of resolution;
 
 abstract class TreeElements {
   Element get currentElement;
   Set<Node> get superUses;
 
@@ skipping 3994 matching lines @@
     return finishConstructorReference(e, node.send.selector, node);
   }
 
   /// Finishes resolution of a constructor reference and records the
   /// type of the constructed instance on [expression].
   FunctionElement finishConstructorReference(Element e,
                                              Node diagnosticNode,
                                              Node expression) {
     // Find the unnamed constructor if the reference resolved to a
     // class.
-    if (!Elements.isUnresolved(e) && e.isClass()) {
-      ClassElement cls = e;
-      cls.ensureResolved(compiler);
-      // The unnamed constructor may not exist, so [e] may become unresolved.
-      e = lookupConstructor(cls, diagnosticNode, const SourceString(''));
+    if (!Elements.isUnresolved(e) && !e.isConstructor()) {
+      if (e.isClass()) {
+        ClassElement cls = e;
+        cls.ensureResolved(compiler);
+        // The unnamed constructor may not exist, so [e] may become unresolved.
+        e = lookupConstructor(cls, diagnosticNode, const SourceString(''));
+      } else {
+        error(diagnosticNode,
+              MessageKind.NOT_A_TYPE.error,
+              {'node': diagnosticNode});
+      }
     }
     if (type == null) {
       if (Elements.isUnresolved(e)) {
         type = compiler.types.dynamicType;
       } else {
         type = e.getEnclosingClass().computeType(compiler).asRaw();
       }
     }
     resolver.mapping.setType(expression, type);
     return e;
@@ skipping 57 matching lines @@
     return e;
   }
 
   /// Assumed to be called by [resolveRedirectingFactory].
   Element visitReturn(Return node) {
     Node expression = node.expression;
     return finishConstructorReference(visit(expression),
                                       expression, expression);
   }
 }