Adding check or trust type checks to builder_kernel.dart.

pkg/compiler/lib/src/ssa/kernel_ast_adapter.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 '../constants/expressions.dart';
 import '../common.dart';
 import '../common/names.dart';
 import '../compiler.dart';
@@ skipping 232 matching lines @@
 
   bool isIntercepted(ir.Node node) {
     Selector selector = getSelector(node);
     return _backend.isInterceptedSelector(selector);
   }
 
   bool isInterceptedSelector(Selector selector) {
     return _backend.isInterceptedSelector(selector);
   }
 
+  LibraryElement get jsHelperLibrary => _backend.helpers.jsHelperLibrary;
+
   JumpTarget getTargetDefinition(ir.Node node) =>
       elements.getTargetDefinition(getNode(node));
 
   ir.Procedure get mapLiteralConstructor =>
       kernel.functions[_backend.helpers.mapLiteralConstructor];
 
   ir.Procedure get mapLiteralConstructorEmpty =>
       kernel.functions[_backend.helpers.mapLiteralConstructorEmpty];
 
   MemberElement get jsIndexableLength => _backend.helpers.jsIndexableLength;
@@ skipping 23 matching lines @@
       .inferredReturnTypeForElement(_backend.helpers.assertThrow, _compiler);
 
   DartType getDartType(ir.DartType type) {
     return type.accept(_typeConverter);
   }
 
   List<DartType> getDartTypes(List<ir.DartType> types) {
     return types.map(getDartType).toList();
   }
 
+  DartType getFunctionReturnType(ir.FunctionNode node) {
+    return getDartType(node.returnType);
+  }
+
   /// Computes the function type corresponding the signature of [node].
   FunctionType getFunctionType(ir.FunctionNode node) {
-    DartType returnType = getDartType(node.returnType);
+    DartType returnType = getFunctionReturnType(node);
     List<DartType> parameterTypes = <DartType>[];
     List<DartType> optionalParameterTypes = <DartType>[];
     for (ir.VariableDeclaration variable in node.positionalParameters) {
       if (parameterTypes.length == node.requiredParameterCount) {
         optionalParameterTypes.add(getDartType(variable.type));
       } else {
         parameterTypes.add(getDartType(variable.type));
       }
     }
     List<String> namedParameters = <String>[];
@@ skipping 357 matching lines @@
     astAdapter.reporter.internalError(
         CURRENT_ELEMENT_SPANNABLE, "Unexpected constant target: $element.");
     return null;
   }
 
   @override
   ConstantExpression visitStringLiteral(ir.StringLiteral node) {
     return new StringConstantExpression(node.value);
   }
 }