Address the remaining review comments on http://chromiumcodereview.appspot.com/9431029.

lib/compiler/implementation/ssa/codegen.dart

 // Copyright (c) 2012, 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.
 
 class SsaCodeGeneratorTask extends CompilerTask {
   SsaCodeGeneratorTask(Compiler compiler) : super(compiler);
   String get name() => 'SSA code generator';
 
 
   String generateMethod(WorkItem work, HGraph graph) {
@@ skipping 1743 matching lines @@
     checkType(input, element);
     buffer.add(')');
     endExpression(JSPrecedence.LOGICAL_OR_PRECEDENCE);
     endExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
   }
 
   void visitIs(HIs node) {
     Type type = node.typeExpression;
     Element element = type.element;
     if (element.kind === ElementKind.TYPE_VARIABLE) {
-      compiler.unimplemented("visitIs for type variables");
+      compiler.unimplemented("visitIs for type variables", instruction: node);
     } else if (element.kind === ElementKind.TYPEDEF) {
-      compiler.unimplemented("visitIs for typedefs");
+      compiler.unimplemented("visitIs for typedefs", instruction: node);
     }
     compiler.registerIsCheck(type.element);
     LibraryElement coreLibrary = compiler.coreLibrary;
     ClassElement objectClass = compiler.objectClass;
     HInstruction input = node.expression;
 
     if (node.nullOk) {
       beginExpression(JSPrecedence.LOGICAL_OR_PRECEDENCE);
       checkNull(input);
       buffer.add(' || ');
@@ skipping 452 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     if (labeledBlockInfo.body.start.hasGuards()) {
       endBailoutSwitch();
     }
   }
 }