Bug 1039586 - Ensure no add-on shim code gets executed when browser.tabs.remote.autostart is false. r=billm,jimm.

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extra : rebase_source : 9e7b62c32e01698992757cca5b6283ed2aa95f27
extra : histedit_source : 404875166004053aca7ccaa805bc616f8910f143