Fix type warning.

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 208 matching lines @@
           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))) {
+      ClassElement clsElement =
+          astAdapter.getElement(constructor).enclosingElement;
       enclosing.typeParameters.forEach((ir.TypeParameter typeParameter) {
         var typeParamElement = astAdapter.getElement(typeParameter);
         HParameterValue param =
             addParameter(typeParamElement, commonMasks.nonNullType);
-        var dart_type = astAdapter.getDartType(typeParameter.bound);
         // This is a little bit wacky (and n^2) until we make the localsHandler
         // take Kernel DartTypes instead of just the AST DartTypes.
-        var typeVariableType = (astAdapter.getElement(constructor))
-            .enclosingElement
+        var typeVariableType = clsElement
             .typeVariables
             .firstWhere((TypeVariableType i) => i.name == typeParameter.name);
         localsHandler.directLocals[
             localsHandler.getTypeVariableAsLocal(typeVariableType)] = param;
       });
     }
   }
 
   /// Builds generative constructors.
   ///
@@ skipping 2090 matching lines @@
     kernelBuilder.open(exitBlock);
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
   }
 }