This reverts commit 9022506292.
Reason for revert: Execute permissions are not required for this file. The error "Uncaught DOMException: Failed to execute 'importScripts' on 'WorkerGlobalScope':" was instead caused by a browser cached version of import returning an incorrect response.
Change-Id: Ib5f6bf30dc5a9919bb7d71fb2b04075486c74f89
Execute permissions are needed on the wasm_exec.js file but nothing seems to set this by default. Once set, it will keep permissions even after rebuilds, but this change will set the initial permissions if required for any new environments.
Change-Id: Ic6848e561210231e67dd2e17a286abdf885926ed