Fix clients being invalid when passed to OnEntityDestroyed (bug 6119, r=KyleS).

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extra : rebase_source : 546168635b7e7cd8f8c4302858aa258025444dfd
Consolidate duplicate OnEntityCreated logic (bug 6119, r=KyleS).

--HG--
extra : rebase_source : b0f563081c5d98c3fbc2769ee89e3ce0ec093624
Fix passing invalid ent to OnEntity forwards (bug 6119, r=KyleS).

--HG--
extra : rebase_source : f5477d7d36ef579c40b0547389e8eccaf129f69e