Fix ArrayShift hydrogen support

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "hydrogen.h"
 
 #include <algorithm>
 
 #include "v8.h"
 #include "allocation-site-scopes.h"
@@ skipping 7909 matching lines @@
 
         if (!ast_context()->IsEffect()) Push(new_size);
         Add<HSimulate>(expr->id(), REMOVABLE_SIMULATE);
         if (!ast_context()->IsEffect()) Drop(1);
       }
 
       ast_context()->ReturnValue(new_size);
       return true;
     }
     case kArrayShift: {
-      // Something in here seems to be causing crbug.com/374838.
-      // TODO(bmeurer): Investigate the problem and re-enable this code.
-      return false;
-
       if (receiver_map.is_null()) return false;
       if (receiver_map->instance_type() != JS_ARRAY_TYPE) return false;
       ElementsKind kind = receiver_map->elements_kind();
       if (!IsFastElementsKind(kind)) return false;
       if (receiver_map->is_observed()) return false;
       ASSERT(receiver_map->is_extensible());
 
       // If there may be elements accessors in the prototype chain, the fast
       // inlined version can't be used.
       if (receiver_map->DictionaryElementsInPrototypeChainOnly()) return false;
@@ skipping 3861 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal