Introduce ParameterStructure

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

Index: pkg/compiler/lib/src/inferrer/closure_tracer.dart
diff --git a/pkg/compiler/lib/src/inferrer/closure_tracer.dart b/pkg/compiler/lib/src/inferrer/closure_tracer.dart
index 83fc2fc78c90a491a64d82f05756097a1460e7aa..d3157ef5978fca01856f05e8a7a0a378415e042d 100644
--- a/pkg/compiler/lib/src/inferrer/closure_tracer.dart
+++ b/pkg/compiler/lib/src/inferrer/closure_tracer.dart
@@ -53,7 +53,8 @@ class ClosureTracerVisitor extends TracerVisitor {
     Selector selector = info.selector;
     TypeMask mask = info.mask;
     tracedElements.forEach((FunctionElement functionElement) {
-      if (!selector.callStructure.signatureApplies(functionElement.type)) {
+      if (!selector.callStructure
+          .signatureApplies(functionElement.parameterStructure)) {
         return;
       }
       inferrer.updateParameterAssignments(