Rename KernelElementAdapter and element_adapter.dart to IrToElementMap and ir_map.dart

tests/compiler/dart2js/kernel/closed_world2_test.dart

 // Copyright (c) 2017, 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.
 
 // Partial test that the closed world computed from [WorldImpact]s derived from
 // kernel is equivalent to the original computed from resolution.
 library dart2js.kernel.closed_world2_test;
 
 import 'dart:async';
 
@@ skipping 19 matching lines @@
 import 'package:compiler/src/js_backend/interceptor_data.dart';
 import 'package:compiler/src/js_backend/lookup_map_analysis.dart';
 import 'package:compiler/src/js_backend/mirrors_analysis.dart'
     hide MirrorsResolutionAnalysisImpl;
 import 'package:compiler/src/js_backend/mirrors_data.dart';
 import 'package:compiler/src/js_backend/no_such_method_registry.dart';
 import 'package:compiler/src/js_backend/resolution_listener.dart';
 import 'package:compiler/src/js_backend/type_variable_handler.dart';
 import 'package:compiler/src/native/enqueue.dart';
 import 'package:compiler/src/native/resolver.dart';
-import 'package:compiler/src/kernel/element_map.dart';
+import 'package:compiler/src/kernel/element_map_impl.dart';
 import 'package:compiler/src/kernel/kernel_strategy.dart';
 import 'package:compiler/src/library_loader.dart';
 import 'package:compiler/src/options.dart';
 import 'package:compiler/src/universe/world_builder.dart';
 import 'package:compiler/src/util/util.dart';
 import 'package:compiler/src/world.dart';
 import 'package:expect/expect.dart';
 import 'package:kernel/ast.dart' as ir;
 import '../memory_compiler.dart';
 import '../serialization/helper.dart';
@@ skipping 95 matching lines @@
   ClosedWorld closedWorld1 = compiler1.resolutionWorldBuilder.closeWorld();
 
   Pair<Compiler, Compiler> compilers =
       await analyzeOnly(entryPoint, memorySourceFiles, printSteps: true);
   Compiler compiler = compilers.a;
   compiler.resolutionWorldBuilder.closeWorld();
   ElementEnvironment environment1 = compiler.elementEnvironment;
 
   Compiler compiler2 = compilers.b;
   KernelFrontEndStrategy frontEndStrategy = compiler2.frontEndStrategy;
-  KernelToElementMap elementMap = frontEndStrategy.elementMap;
+  KernelToElementMapImpl elementMap = frontEndStrategy.elementMap;
   Expect.isFalse(compiler2.compilationFailed);
 
   KernelEquivalence equivalence = new KernelEquivalence(elementMap);
 
   ElementEnvironment environment2 = compiler2.elementEnvironment;
   checkElementEnvironment(environment1, environment2, equivalence);
 
   ResolutionEnqueuer enqueuer2 = compiler2.enqueuer.resolution;
   BackendUsage backendUsage2 = compiler2.backend.backendUsage;
   ClosedWorld closedWorld2 = compiler2.resolutionWorldBuilder.closeWorld();
@@ skipping 133 matching lines @@
 
       classes2.add(cls2);
     });
     env2.forEachClass(lib2, (ClassEntity cls2) {
       Expect.isTrue(classes2.contains(cls2), "Extra class $cls2 in $lib2");
     });
   });
 
   // TODO(johnniwinther): Test the remaining properties of [ElementEnvironment].
 }