Codegen support for the argument definition test.

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 1697 matching lines @@
       } else if (constant.isString()) {
         // TODO(floitsch): get rid of the code buffer.
         CodeBuffer buffer = new CodeBuffer();
         handler.writeConstant(buffer, constant);
         push(new js.LiteralString(buffer.toString()));
       } else if (constant.isFunction()) {
         FunctionConstant function = constant;
         world.registerStaticUse(function.element);
         push(new js.VariableUse(
             compiler.namer.isolateAccess(function.element)));
+      } else if (constant.isSentinel()) {
+        // TODO(floitsch): get rid of the code buffer.
+        CodeBuffer buffer = new CodeBuffer();
+        handler.writeConstant(buffer, constant);
+        push(new js.VariableUse(buffer.toString()));
       } else {
         compiler.internalError(
             "The compiler does not know how generate code for "
             "constant $constant");
       }
     } else {
       js.VariableUse currentIsolateUse =
           new js.VariableUse(compiler.namer.CURRENT_ISOLATE);
       push(new js.PropertyAccess.field(currentIsolateUse, name));
     }
@@ skipping 1167 matching lines @@
   if (leftType.canBeNull() && rightType.canBeNull()) {
     if (left.isConstantNull() || right.isConstantNull() ||
         (leftType.isPrimitive() && leftType == rightType)) {
       return '==';
     }
     return null;
   } else {
     return '===';
   }
 }