Fix an issue discovered in regress-969.

When running with 10 stress runs we get polymorphic stores.  This revealed
an incorrect bailout ID for the state following a polymorphic store.  The ID
should be the internal ID of the assignment side-effect, not the ID of the
end of the expression.

Review URL: http://codereview.chromium.org/5885003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6051 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen.cc

@@ -3257,7 +3257,7 @@ void HGraphBuilder::HandlePolymorphicStoreNamedField(Assignment* expr,
     }
 
     HBasicBlock* new_exit_block =
-        BuildTypeSwitch(&maps, &subgraphs, object, expr->id());
+        BuildTypeSwitch(&maps, &subgraphs, object, expr->AssignmentId());
     subgraph()->set_exit_block(new_exit_block);
   }