Increase tracing limit

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

 // Copyright (c) 2013, 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.
 
 library compiler.src.inferrer.node_tracer;
 
 import '../common/names.dart' show Identifiers;
 import '../compiler.dart' show Compiler;
 import '../elements/elements.dart';
 import '../types/types.dart' show ContainerTypeMask, MapTypeMask;
@@ skipping 59 matching lines @@
   // [keys] only allows key values to escape, which we do not track.
   'keys'
 ]);
 
 /// Common logic to trace a value through the type inference graph nodes.
 abstract class TracerVisitor implements TypeInformationVisitor {
   final TypeInformation tracedType;
   final InferrerEngine inferrer;
   final Compiler compiler;
 
-  static const int MAX_ANALYSIS_COUNT = 16;
+  static const int MAX_ANALYSIS_COUNT =
+      const int.fromEnvironment('dart2js.tracing.limit', defaultValue: 32);
   final Setlet<Element> analyzedElements = new Setlet<Element>();
 
   TracerVisitor(this.tracedType, InferrerEngine inferrer)
       : this.inferrer = inferrer,
         this.compiler = inferrer.compiler;
 
   // Work list that gets populated with [TypeInformation] that could
   // contain the container.
   final List<TypeInformation> workList = <TypeInformation>[];
 
@@ skipping 377 matching lines @@
     }
     if (isParameterOfListAddingMethod(element) ||
         isParameterOfMapAddingMethod(element)) {
       // These elements are being handled in
       // [visitDynamicCallSiteTypeInformation].
       return;
     }
     addNewEscapeInformation(info);
   }
 }