Add support for converted closures with explicit contexts to VM

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

Index: pkg/kernel/lib/transformations/closure/converter.dart
diff --git a/pkg/kernel/lib/transformations/closure/converter.dart b/pkg/kernel/lib/transformations/closure/converter.dart
index c879627c28b40771a50030dd3bf047f21fb886c0..5ee224172f0006729dda2786a0733ec62dadfdff 100644
--- a/pkg/kernel/lib/transformations/closure/converter.dart
+++ b/pkg/kernel/lib/transformations/closure/converter.dart
@@ -236,6 +236,15 @@ class ClosureConverter extends Transformer {
     return type is InterfaceType && type.classNode.supertype == null;
   }
 
+  TreeNode visitField(Field node) {
+    currentMember = node;
+    context = new NoContext(this);
+    node = super.visitField(node);
+    context = null;
+    currentMember = null;
+    return node;
+  }
+
   Expression handleLocalFunction(FunctionNode function) {
     FunctionNode enclosingFunction = currentFunction;
     Map<TypeParameter, DartType> enclosingTypeSubstitution = typeSubstitution;
@@ -430,7 +439,7 @@ class ClosureConverter extends Transformer {
   TreeNode visitBlock(Block node) {
     return saveContext(() {
       BlockRewriter blockRewriter = rewriter = rewriter.forNestedBlock(node);
-      blockRewriter.transformStatements(node, this);
+      blockRewriter.transformStatements(this);
       return node;
     });
   }