Use entities in CommonElements interface.

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, CodegenWorkItem;
 import '../common/names.dart';
@@ skipping 210 matching lines @@
     closeFunction();
   }
 
   /// Pops the most recent instruction from the stack and 'boolifies' it.
   ///
   /// Boolification is checking if the value is '=== true'.
   @override
   HInstruction popBoolified() {
     HInstruction value = pop();
     if (typeBuilder.checkOrTrustTypes) {
-      return typeBuilder.potentiallyCheckOrTrustType(
-          value, compiler.commonElements.boolType,
+      ResolutionInterfaceType type = compiler.commonElements.boolType;
+      return typeBuilder.potentiallyCheckOrTrustType(value, type,
           kind: HTypeConversion.BOOLEAN_CONVERSION_CHECK);
     }
     HInstruction result = new HBoolify(value, commonMasks.boolType);
     add(result);
     return result;
   }
 
   void _addClassTypeVariablesIfNeeded(ir.Member constructor) {
     var enclosing = constructor.enclosingClass;
     if (backend.classNeedsRti(astAdapter.getElement(enclosing))) {
@@ skipping 2847 matching lines @@
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
     kernelBuilder.inTryStatement = previouslyInTryStatement;
   }
 }