Convert closures in all initializers, and share the context between them.

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

 // Copyright (c) 2016, 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 kernel.transformations.closure.info;
 
 import '../../ast.dart'
     show
         Class,
         Constructor,
         Field,
         FunctionDeclaration,
         FunctionNode,
         Member,
         Name,
         Procedure,
         ProcedureKind,
         PropertyGet,
         ThisExpression,
         TypeParameter,
         TypeParameterType,
         VariableDeclaration,
         VariableGet,
-        VariableSet;
+        VariableSet,
+        visitList;
 
 import '../../visitor.dart' show RecursiveVisitor;
 
 class ClosureInfo extends RecursiveVisitor {
   FunctionNode currentFunction;
   final Map<VariableDeclaration, FunctionNode> function =
       <VariableDeclaration, FunctionNode>{};
 
   final Set<VariableDeclaration> variables = new Set<VariableDeclaration>();
 
@@ skipping 77 matching lines @@
     ///         /* Constructor body. */
     ///       }
     ///     }
     ///
     /// Here the parameter shouldn't be captured into a context in the
     /// initializer.  However, [currentFunction] is `null` if not set, and
     /// `function[node.variable]` in this case points to the [FunctionNode] of
     /// the constructor (which is not `null`).  It leads to `x` being treated as
     /// captured, because it's seen as used outside of the function where it is
     /// declared.  In turn, it leads to unnecessary context creation and usage.
+    ///
+    /// We also need to visit the parameters to the function node before the
+    /// initializer list. Since the default [visitChildren] method of
+    /// [Constructor] will visit initializers first, we manually visit the
+    /// parameters here.
+    ///
+    /// TODO(sjindel): Don't visit the parameters twice.
+    ///
     beginMember(node, node.function);
     saveCurrentFunction(() {
       currentFunction = currentMemberFunction;
+      visitList(node.function.positionalParameters, this);
+      visitList(node.function.namedParameters, this);
       super.visitConstructor(node);
     });
     endMember();
   }
 
   visitProcedure(Procedure node) {
     beginMember(node, node.function);
     if (node.isInstanceMember && node.kind == ProcedureKind.Method) {
       // Ignore the `length` method of [File] subclasses for now, as they
       // will force us to rename the `length` getter (kernel issue #43).
@@ skipping 101 matching lines @@
 
   saveCurrentFunction(void f()) {
     var saved = currentFunction;
     try {
       f();
     } finally {
       currentFunction = saved;
     }
   }
 }