Make sure that the context argument of HAdd is never NULL.

src/hydrogen.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 3549 matching lines @@
   void BuildOffsetAdd(HBoundsCheck* check,
                       HAdd** add,
                       HConstant** constant,
                       HValue* original_value,
                       Representation representation,
                       int32_t new_offset) {
     HConstant* new_constant = new(BasicBlock()->zone())
        HConstant(new_offset, Representation::Integer32());
     if (*add == NULL) {
       new_constant->InsertBefore(check);
-      *add = new(BasicBlock()->zone()) HAdd(NULL,
+      // Because of the bounds checks elimination algorithm, the index is always
+      // an HAdd or an HSub here, so we can safely cast to an HBinaryOperation.
+      HValue* context = HBinaryOperation::cast(check->index())->context();
+      *add = new(BasicBlock()->zone()) HAdd(context,
                                             original_value,
                                             new_constant);
       (*add)->AssumeRepresentation(representation);
       (*add)->InsertBefore(check);
     } else {
       new_constant->InsertBefore(*add);
       (*constant)->DeleteAndReplaceWith(new_constant);
     }
     *constant = new_constant;
   }
@@ skipping 6356 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal