Split getClosureRepresentationInfo into MemberEntity and (ir/ast) nodes

pkg/compiler/lib/src/ssa/builder.dart

 // Copyright (c) 2012, 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.
 
 import 'dart:collection';
 
 import 'package:js_runtime/shared/embedded_names.dart';
 
 import '../closure.dart';
 import '../common.dart';
@@ skipping 1848 matching lines @@
           block.addAtExit(new HBreak.toLabel(label));
           block.remove(breakInstruction);
         });
       }
     }
     jumpHandler.close();
     loopDepth--;
   }
 
   visitFunctionExpression(ast.FunctionExpression node) {
-    LocalFunctionElement methodElement = elements[node];
     ClosureRepresentationInfo closureInfo =
-        closureDataLookup.getClosureRepresentationInfo(methodElement);
+        closureDataLookup.getClosureInfo(node);
     ClassEntity closureClassEntity = closureInfo.closureClassEntity;
 
     List<HInstruction> capturedVariables = <HInstruction>[];
     closureInfo.createdFieldEntities.forEach((Local field) {
       assert(field != null);
       capturedVariables.add(localsHandler.readLocal(field));
     });
 
     TypeMask type = new TypeMask.nonNullExact(closureClassEntity, closedWorld);
     push(new HCreate(closureClassEntity, capturedVariables, type,
@@ skipping 4958 matching lines @@
       this.oldReturnLocal,
       this.oldReturnType,
       this.oldResolvedAst,
       this.oldStack,
       this.oldLocalsHandler,
       this.inTryStatement,
       this.allFunctionsCalledOnce,
       this.oldElementInferenceResults)
       : super(function);
 }