Bug 1029031 - Fix Beta-only race condition in browser_urlbar_search_healthreport.js; r=me, a=test-only

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extra : rebase_source : 88c38a09645564e132f1d45636a0084dd074c3a9
extra : amend_source : aede97e39cca5d38d1c122ab309c1de6c8e513b3