Increase tracing limit

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

Index: pkg/compiler/lib/src/inferrer/node_tracer.dart
diff --git a/pkg/compiler/lib/src/inferrer/node_tracer.dart b/pkg/compiler/lib/src/inferrer/node_tracer.dart
index 013b53f7c62515235e4a8498d28f5f7cfdf430e4..64f5c2bfab16d41da6b200b6d1a9cd24670e3159 100644
--- a/pkg/compiler/lib/src/inferrer/node_tracer.dart
+++ b/pkg/compiler/lib/src/inferrer/node_tracer.dart
@@ -77,7 +77,8 @@ abstract class TracerVisitor implements TypeInformationVisitor {
   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)