[show-hint addon] Fix a typo
Don't mess up the display when updateDisplay is given a negative top offset

Issue #2554
[css mode] Add object-fit and object-position properties
[css mode] Better handling of parentheses in property values

Issue #2551
Fix typo in manual
[closetag addon] Improve heuristic for seeing if closing tag already exists

Issue #2557
Make ctrl-drag copy text

Issue #2556
Ensure a viewport always contains a single line
[tern addon] Improve alignment of completion docs
[tern addon] Remove unnecessary error check
[tern addon] Lint fix
merge