Fix type tests for null.

sdk/lib/_internal/compiler/implementation/ssa/builder.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.
 
 part of ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 3096 matching lines @@
     } else if (name == const SourceString('DART_CLOSURE_TO_JS')) {
       handleForeignDartClosureToJs(node, 'DART_CLOSURE_TO_JS');
     } else if (name == const SourceString('RAW_DART_FUNCTION_REF')) {
       handleForeignRawFunctionRef(node, 'RAW_DART_FUNCTION_REF');
     } else if (name == const SourceString('JS_SET_CURRENT_ISOLATE')) {
       handleForeignSetCurrentIsolate(node);
     } else if (name == const SourceString('JS_CREATE_ISOLATE')) {
       handleForeignCreateIsolate(node);
     } else if (name == const SourceString('JS_OPERATOR_IS_PREFIX')) {
       stack.add(addConstantString(node, backend.namer.operatorIsPrefix()));
+    } else if (name == const SourceString('JS_OBJECT_CLASS_NAME')) {
+      String name = backend.namer.getRuntimeTypeName(compiler.objectClass);
+      stack.add(addConstantString(node, name));
     } else if (name == const SourceString('JS_OPERATOR_AS_PREFIX')) {
       stack.add(addConstantString(node, backend.namer.operatorAsPrefix()));
     } else if (name == const SourceString('JS_DART_OBJECT_CONSTRUCTOR')) {
       handleForeignDartObjectJsConstructorFunction(node);
     } else if (name == const SourceString('JS_IS_INDEXABLE_FIELD_NAME')) {
       Element element = compiler.findHelper(
           const SourceString('JavaScriptIndexingBehavior'));
       stack.add(addConstantString(node, backend.namer.operatorIs(element)));
     } else {
       throw "Unknown foreign: ${selector}";
@@ skipping 2245 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }