Support closures inside initializers.

lib/compiler/implementation/closure.dart

Index: lib/compiler/implementation/closure.dart
===================================================================
--- lib/compiler/implementation/closure.dart	(revision 14321)
+++ lib/compiler/implementation/closure.dart	(working copy)
@@ -45,9 +45,7 @@
     return measure(() {
       ClosureClassMap nestedClosureData = closureMappingCache[node];
       if (nestedClosureData == null) {
-        // TODO(floitsch): we can only assume that the reason for not having a
-        // closure data here is, because the function is inside an initializer.
-        compiler.unimplemented("Closures inside initializers", node: node);
+        compiler.internalError("No closure cache", node: node);
       }
       return nestedClosureData;
     });
@@ -610,9 +608,8 @@
       // TODO(ahe): This is problematic. The backend should not repeat
       // the work of the resolver. It is the resolver's job to create
       // parameters, etc. Other phases should only visit statements.
-      // TODO(floitsch): we avoid visiting the initializers on purpose so that
-      // we get an error-message later in the builder.
       if (node.parameters != null) node.parameters.accept(this);
+      if (node.initializers != null) node.initializers.accept(this);
       if (node.body != null) node.body.accept(this);
     });
   }