Let the inferrer know that lazy variables can also be null incase their initializer throws.

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 436 matching lines @@
     }
     ResolverVisitor visitor = visitorFor(element);
     visitor.useElement(tree, element);
 
     // TODO(johnniwinther): Avoid analyzing initializers if
     // [Compiler.analyzeSignaturesOnly] is set.
     initializerDo(tree, visitor.visit);
 
     if (Elements.isStaticOrTopLevelField(element)) {
       if (tree.asSendSet() != null) {
-        // TODO(ngeoffray): We could do better here by using the
+        // TODO(13429): We could do better here by using the
         // constant handler to figure out if it's a lazy field or not.
         compiler.backend.registerLazyField(visitor.mapping);
       } else {
         compiler.enqueuer.resolution.registerInstantiatedClass(
             compiler.nullClass, visitor.mapping);
       }
     }
 
     // Perform various checks as side effect of "computing" the type.
     element.computeType(compiler);
@@ skipping 3874 matching lines @@
     return e;
   }
 
   /// Assumed to be called by [resolveRedirectingFactory].
   Element visitReturn(Return node) {
     Node expression = node.expression;
     return finishConstructorReference(visit(expression),
                                       expression, expression);
   }
 }