Bug 895174 - defect - not able to scroll list of recent history in snap view r=mbrubeck

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extra : rebase_source : 8b30ed307f7a91c7610a03613fd53ad627a398a0
Bug 892046 - Reuse the start UI views for snapped view
Bug 892046 - part 2
Bug 629668 - make ipdl.py check timestamps to determine whether parsing/codegen is necessary; r=bent