Fix the locals lookup of variables and partial implementation of boxing of variables.

pkg/compiler/lib/src/kernel/element_map.dart

Index: pkg/compiler/lib/src/kernel/element_map.dart
diff --git a/pkg/compiler/lib/src/kernel/element_map.dart b/pkg/compiler/lib/src/kernel/element_map.dart
index 9bad04ee9de5a80a1acafda382e328c4b7ed90de..8f7cc42b88f635f3b24a4a7aec23a01e22ddb343 100644
--- a/pkg/compiler/lib/src/kernel/element_map.dart
+++ b/pkg/compiler/lib/src/kernel/element_map.dart
@@ -244,6 +244,9 @@ abstract class MemberDefinition {
 enum ClassKind {
   regular,
   closure,
+  // TODO(efortuna, johnniwinther): Container is not a class, but is
+  // masquerading as one currently for consistency with the old element model.
+  container,
 }
 
 /// A member directly defined by its [ir.Member] node.
@@ -383,8 +386,12 @@ abstract class KernelToLocalsMap {
   /// Call to notify that [member] is no longer being inlined.
   void leaveInlinedMember(covariant MemberEntity member);
 
-  /// Returns the [Local] for [node].
-  Local getLocalVariable(ir.VariableDeclaration node);
+  /// Returns the [Local] for [node]. If [isClosureCallMethod] is true, this
+  /// gives the locals map permission to also look one scope higher within the
+  /// class for the corresponding local. This can happen in the case of free
+  /// variables involved with a closure class.
+  Local getLocalVariable(ir.VariableDeclaration node,
+      {bool isClosureCallMethod = false});
 
   /// Returns the [Local] corresponding to the [node]. The node must be either
   /// a [ir.FunctionDeclaration] or [ir.FunctionExpression].