Move main and isolate handling to enqueuer listeners.

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 181 matching lines @@
       } else {
         buildConstructor(target);
       }
     } else if (target is ir.FunctionExpression) {
       _targetFunction = (target as ir.FunctionExpression).function;
       buildFunctionNode(_targetFunction);
     } else if (target is ir.FunctionDeclaration) {
       _targetFunction = (target as ir.FunctionDeclaration).function;
       buildFunctionNode(_targetFunction);
     } else {
-      throw 'No case implemented to handle target: $target';
+      throw 'No case implemented to handle target: $target for $targetElement';
     }
     assert(graph.isValid());
     return graph;
   }
 
   void buildField(ir.Field field) {
     openFunction();
     if (field.initializer != null) {
       field.initializer.accept(this);
       HInstruction fieldValue = pop();
@@ skipping 3040 matching lines @@
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
     kernelBuilder.inTryStatement = previouslyInTryStatement;
   }
 }