Merge pull request #8915 from crdlc/bug-856584

Bug 856584 - Regression 845487 - postMessage for workers does not suppor...(cherry picked from commit 4fbf53318c32e27cdbf79ee23955298860ed42e7)
(cherry picked from commit da97273e1dc6bbfde20f026834bd0388cde56b91)