Move computation of method flags into model.

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

 // Copyright (c) 2011, 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 js_backend;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  */
 class Namer implements ClosureNamer {
@@ skipping 847 matching lines @@
     return userGlobalObjects[
         library.getLibraryOrScriptName().hashCode % userGlobalObjects.length];
   }
 
   String getLazyInitializerName(Element element) {
     assert(Elements.isStaticOrTopLevelField(element));
     return getMappedGlobalName("$getterPrefix${getNameX(element)}");
   }
 
   String getStaticClosureName(Element element) {
-    assert(Elements.isStaticOrTopLevelFunction(element));
+    assert(invariant(element, Elements.isStaticOrTopLevelFunction(element)));
     return getMappedGlobalName("${getNameX(element)}\$closure");
   }
 
   // This name is used as part of the name of a TypeConstant
   String uniqueNameForTypeConstantElement(Element element) {
     // TODO(sra): If we replace the period with an identifier character,
     // TypeConstants will have better names in unminified code.
     return "${globalObjectFor(element)}.${getNameX(element)}";
   }
 
@@ skipping 537 matching lines @@
         if (!first) {
           sb.write('_');
         }
         sb.write('_');
         visit(parameter);
         first = true;
       }
     }
   }
 }