Support parameter access in analyzer2dart.

sdk/lib/_internal/compiler/implementation/cps_ir/cps_ir_builder.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.ir_builder;
 
 import 'cps_ir_nodes.dart' as ir;
 import '../elements/elements.dart';
 import '../dart2jslib.dart';
 import '../dart_types.dart';
@@ skipping 352 matching lines @@
   ir.Constant buildNullLiteral() {
     return buildPrimConst(constantSystem.createNull());
   }
 
   /// Create a string literal.
   ir.Constant buildStringLiteral(String value) {
     return buildPrimConst(
         constantSystem.createString(new ast.DartString.literal(value)));
   }
 
+  /// Create a get access of [local].
+  ir.Primitive buildGetLocal(Element local) {
+    assert(isOpen);
+    return environment.lookup(local);
+  }
+
   /**
    * Add an explicit `return null` for functions that don't have a return
    * statement on each branch. This includes functions with an empty body,
    * such as `foo(){ }`.
    */
   void ensureReturn() {
     if (!isOpen) return;
     ir.Constant constant = makePrimConst(constantSystem.createNull());
     add(new ir.LetPrim(constant));
     add(new ir.InvokeContinuation(returnContinuation, [constant]));
@@ skipping 947 matching lines @@
 
     if (element != null && element.isConst) {
       // Reference to constant local, top-level or static field
       result = translateConstant(node);
     } else if (isClosureVariable(element)) {
       LocalElement local = element;
       result = new ir.GetClosureVariable(local);
       add(new ir.LetPrim(result));
     } else if (Elements.isLocal(element)) {
       // Reference to local variable
-      result = environment.lookup(element);
+      result = buildGetLocal(element);
     } else if (element == null ||
                Elements.isInstanceField(element) ||
                Elements.isInstanceMethod(element) ||
                selector.isIndex ||
                // TODO(johnniwinther): clean up semantics of resultion.
                node.isSuperCall) {
       // Dynamic dispatch to a getter. Sometimes resolution will suggest a
       // target element, but in these cases we must still emit a dynamic
       // dispatch. The target element may be an instance method in case we are
       // converting a method to a function object.
@@ skipping 627 matching lines @@
   }
 
   visitFunctionExpression(ast.FunctionExpression node) {
     FunctionElement oldFunction = currentFunction;
     currentFunction = elements[node];
     visit(node.body);
     currentFunction = oldFunction;
   }
 
 }