Fix for issue 4921: ad the generic type info to a List when we create it.

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 {
 
   final JavaScriptBackend backend;
 
   SsaCodeGeneratorTask(JavaScriptBackend backend)
       : this.backend = backend,
@@ skipping 2359 matching lines @@
       js.Expression result = pop();
       for (TypeVariableType typeVariable in cls.typeVariables) {
         use(node.typeInfoCall);
         // TODO(johnniwinther): Retrieve the type name properly and not through
         // [toString]. Note: Two cases below [typeVariable] and
         // [arguments.head].
         js.PropertyAccess field =
             new js.PropertyAccess.field(pop(), typeVariable.toString());
         js.Expression genericName = new js.LiteralString("'${arguments.head}'");
         js.Binary eqTest = new js.Binary('===', field, genericName);
-        result = new js.Binary('&&', result, eqTest);
+        js.Prefix nullTest = new js.Prefix('!', field);

[kasperl, 2012/09/12 12:19:04]

Add a comment that explains why it is necessary to allow the non-exisiting type
field to pass as true? Maybe do null test before eq test? Seems a bit more
logical.

[ngeoffray, 2012/09/12 12:30:39]

Done.

+        result = new js.Binary(
+            '&&', result, new js.Binary('||', eqTest, nullTest));
       }
       push(result, node);
     }
     if (node.nullOk) {
       checkNull(input);
       push(new js.Binary('||', pop(), pop()), node);
     }
   }
 
   void visitTypeConversion(HTypeConversion node) {
@@ skipping 590 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }