Fix broken HCheckInstanceType::Canonicalize().

src/hydrogen-instructions.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1615 matching lines @@
       // Return NULL to remove this instruction from the graph.
       return NULL;
     }
   }
   return this;
 }
 
 
 HValue* HCheckInstanceType::Canonicalize() {
   if (check_ == IS_STRING && value()->type().IsString()) {
-    return NULL;
+    return value();
   }
 
   if (check_ == IS_INTERNALIZED_STRING && value()->IsConstant()) {
-    if (HConstant::cast(value())->HasInternalizedStringValue()) return NULL;
+    if (HConstant::cast(value())->HasInternalizedStringValue()) {
+      return value();
+    }
   }
   return this;
 }
 
 
 void HCheckInstanceType::GetCheckInterval(InstanceType* first,
                                           InstanceType* last) {
   ASSERT(is_interval_check());
   switch (check_) {
     case IS_SPEC_OBJECT:
@@ skipping 2818 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal