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

pkg/compiler/lib/src/js_model/elements.dart

Index: pkg/compiler/lib/src/js_model/elements.dart
diff --git a/pkg/compiler/lib/src/js_model/elements.dart b/pkg/compiler/lib/src/js_model/elements.dart
index 36e690187c7382bae2dca60dbcef2b4947aa6586..f91a3fda8225adb72dc0484de78962f73c291e0a 100644
--- a/pkg/compiler/lib/src/js_model/elements.dart
+++ b/pkg/compiler/lib/src/js_model/elements.dart
@@ -319,7 +319,8 @@ class JClass implements ClassEntity, IndexedClass {
 
   JClass(this.library, this.classIndex, this.name, {this.isAbstract});
 
-  @override
+  /// True if this class is a class created to represent the semantics of a Dart
+  /// closure.
   bool get isClosure => false;
 
   String toString() => '${jsElementPrefix}class($name)';
@@ -547,9 +548,16 @@ class JField extends JMember implements FieldEntity, IndexedField {
 class JClosureCallMethod extends JMethod {
   JClosureCallMethod(int memberIndex, KernelClosureClass containingClass,
       ParameterStructure parameterStructure, AsyncMarker asyncMarker)
-      : super(memberIndex, containingClass.library, containingClass, Names.call,
-            parameterStructure, asyncMarker,
-            isStatic: false, isExternal: false, isAbstract: false);
+      : super(
+            memberIndex,
+            containingClass.closureClassEntity.library,
+            containingClass.closureClassEntity,
+            Names.call,
+            parameterStructure,
+            asyncMarker,
+            isStatic: false,
+            isExternal: false,
+            isAbstract: false);
 
   String get _kind => 'closure_call';
 }