Split KernelToElementMap into sub-interfaces

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

 // Copyright (c) 2016, 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 'package:kernel/ast.dart' as ir;
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry;
 import '../common/names.dart';
@@ skipping 69 matching lines @@
 
   final Compiler compiler;
 
   @override
   JavaScriptBackend get backend => compiler.backend;
 
   @override
   TreeElements get elements => astAdapter.elements;
 
   SourceInformationBuilder sourceInformationBuilder;
-  final KernelToElementMap _elementMap;
+  final KernelToElementMapForBuilding _elementMap;
   final KernelToTypeInferenceMap _typeInferenceMap;
   final KernelToLocalsMap localsMap;
   LoopHandler<ir.Node> loopHandler;
   TypeBuilder typeBuilder;
 
   final Map<ir.VariableDeclaration, HInstruction> letBindings =
       <ir.VariableDeclaration, HInstruction>{};
 
   /// True if we are visiting the expression of a throw statement; we assume
   /// this is a slow path.
@@ skipping 3382 matching lines @@
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
     kernelBuilder.inTryStatement = previouslyInTryStatement;
   }
 }