Fix a bug in how we deal HTypeConversion during type propagation: we must use the intersection betw…

sdk/lib/_internal/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.
 
 part of ssa;
 
 class SsaCodeGeneratorTask extends CompilerTask {
 
   final JavaScriptBackend backend;
 
@@ skipping 2476 matching lines @@
     }
     return test;
   }
 
   void visitTypeConversion(HTypeConversion node) {
     if (!node.isChecked) {
       use(node.checkedInput);
       return;
     }
     if (node.isArgumentTypeCheck || node.isReceiverTypeCheck) {
+      // An int check if the input is not int or null, is not
+      // sufficient for doing a argument or receiver check.
+      assert(!node.isInteger() || node.checkedInput.isIntegerOrNull());
       js.Expression test = generateTest(node);
       js.Block oldContainer = currentContainer;
       js.Statement body = new js.Block.empty();
       currentContainer = body;
       if (node.isArgumentTypeCheck) {
         generateThrowWithHelper('iae', node.checkedInput);
       } else if (node.isReceiverTypeCheck) {
         use(node.checkedInput);
         String methodName =
             backend.namer.invocationName(node.receiverTypeCheckSelector);
@@ skipping 505 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive(compiler) && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }