Bug 828207: Wallpaper over not being able to find a layer manager on the main thread when initializing a remote render frame.  That's OK, we'll find one on the compositor thread. r=cjones
Fix for bug 828180 (crash in nsIContent::IsHTML). r=bz.

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extra : rebase_source : 677b29a45cb1d19b8e793b4dc4e4bb9f7006fafa