Improve the performance of closure-converted code.

pkg/kernel/lib/transformations/closure/context.dart

Index: pkg/kernel/lib/transformations/closure/context.dart
diff --git a/pkg/kernel/lib/transformations/closure/context.dart b/pkg/kernel/lib/transformations/closure/context.dart
index 3e4ed1790904785fa56979252c480ee6682998b1..ee8fc6751b24fac9ac69000eeb37bf93f1c16c2c 100644
--- a/pkg/kernel/lib/transformations/closure/context.dart
+++ b/pkg/kernel/lib/transformations/closure/context.dart
@@ -7,6 +7,7 @@ library kernel.transformations.closure.context;
 import '../../ast.dart'
     show
         Expression,
+        FunctionNode,
         NullLiteral,
         StringLiteral,
         Throw,
@@ -137,6 +138,9 @@ class LocalContext extends Context {
     value.parent = initializer;
 
     converter.rewriter.insertExtendContext(initializer);
+    if (variable.parent is FunctionNode) {
+      converter.rewriter.insertZeroOutParameter(variable);
+    }
 
     ++vectorCreation.length;
     variables.add(variable);