Preserve type variables in closure conversion.

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

Index: pkg/kernel/lib/transformations/closure/info.dart
diff --git a/pkg/kernel/lib/transformations/closure/info.dart b/pkg/kernel/lib/transformations/closure/info.dart
index 68b82c1dc5e51e0c5fd4393e813aafc780f3a49d..e2eda7861664f2e0b7f353c97efc1647ea081bea 100644
--- a/pkg/kernel/lib/transformations/closure/info.dart
+++ b/pkg/kernel/lib/transformations/closure/info.dart
@@ -30,6 +30,7 @@ class ClosureInfo extends RecursiveVisitor {
 
   final Set<VariableDeclaration> variables = new Set<VariableDeclaration>();
 
+  /// Map from functions to set of type variables captured within them.
   final Map<FunctionNode, Set<TypeParameter>> typeVariables =
       <FunctionNode, Set<TypeParameter>>{};
 
@@ -166,7 +167,10 @@ class ClosureInfo extends RecursiveVisitor {
       // Propagate captured type variables to enclosing function.
       typeVariables
           .putIfAbsent(currentFunction, () => new Set<TypeParameter>())
-          .addAll(capturedTypeVariables);
+          .addAll(
+              // [t.parent == currentFunction] will be true if the type variable
+              // is defined by one of our type parameters.
+              capturedTypeVariables.where((t) => t.parent != currentFunction));
     }
   }
 
@@ -190,7 +194,7 @@ class ClosureInfo extends RecursiveVisitor {
   }
 
   visitTypeParameterType(TypeParameterType node) {
-    if (!isOuterMostContext) {
+    if (!isOuterMostContext && node.parameter.parent != currentFunction) {
       typeVariables
           .putIfAbsent(currentFunction, () => new Set<TypeParameter>())
           .add(node.parameter);