Remove use of !==

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 operator[](Node node);
   Selector getSelector(Send send);
   DartType getType(Node node);
@@ skipping 2788 matching lines @@
   /**
    * Adds [type] and all supertypes of [type] to [builder] while substituting
    * type variables.
    */
   void addAllSupertypes(LinkBuilder<DartType> builder, InterfaceType type) {
     builder.addLast(type);
     Link<DartType> typeArguments = type.typeArguments;
     ClassElement classElement = type.element;
     Link<DartType> typeVariables = classElement.typeVariables;
     Link<DartType> supertypes = classElement.allSupertypes;
-    assert(invariant(element, supertypes !== null,
+    assert(invariant(element, supertypes != null,
         message: "Supertypes not computed on $classElement "
                  "during resolution of $element"));
     while (!supertypes.isEmpty) {
       DartType supertype = supertypes.head;
       builder.addLast(supertype.subst(typeArguments, typeVariables));
       supertypes = supertypes.tail;
     }
   }
 
   /**
@@ skipping 498 matching lines @@
     return e;
   }
 
   /// Assumed to be called by [resolveRedirectingFactory].
   Element visitReturn(Return node) {
     Node expression = node.expression;
     return finishConstructorReference(visit(expression),
                                       expression, expression);
   }
 }