The function is confusing and added unnecessary complexity, given that it is
only called in one place, and is not a function that should be exposed to
other modules.
The original had two bugs in this line of code that cancelled each other
out. 4d0f304 fixed one, causing hotspots to no longer appear. This commit
fixes the second.
This commit extends the `compute_placement()` function in
`popovers.js` to take into account height/width of popover as well as
positioning preference. If vertical positioning is desired and the
popover fits in either 'top/bottom' positions then we don't check for
`left/right' positions. Earlier the behavior was to prefer
'left/right'positions over 'top/bottom' positions, which resulted in
the emoji picker popping incorrectly to the left.
compute_placement utilizes the dimensions of the viewport, viewport location of
an element, and dimensions of an element to determine if a popover will fit
horizontally and/or veritically given its orientation. The default placement
is now viewport_center, which displays the popover, without an arrow, in the
fixed center of the viewport.
This should be particularly useful for hotspots on mobile or large popovers
that contain a lot of content. The property hotspot.location.popover can be
optionally set to fix the orientation of a popover (most likely to
VIEWPORT_CENTER).
This commit adds the backend support for a new style of tutorial which
allows for highlighting of multiple areas of the page with hotspots that
disappear when clicked by the user.
