Includes:
- change .stopped method to .isStopped() for
consistency
- replace code in checkResize that adjusts
dimensions for setElementDimensions
- add code that deals with the window size being
too small to run whenever positions are calculated
- add reset method for when screen is too small
for sticking behaviour
- move guard out of methods for stopping and
sticking (it hid info that was useful at the
point they were called)
Allows other JS to tell sticky elements to
recalculate their dimensions and then position
(and then check to see if their state needs
changing).
We need this because we change the content of our
element so its dimensions change.
The recalculation code also updates the shim for
elements that are 'stuck' so the horizontal space
the element would occupy in the flow of the page
is correct.
Includes other code that splits the height
StickyElement stores into two properties:
1. `verticalSpace`
2. `height`
`verticalSpace` is the vertical space the element
occupies in the document flow when not stuck.
`height` is the visual space of the element,
including padding and border.
We ‘shim’ the sticky element so that its space in the page is reserved
while it is sticky.
This means the shim have have the same height as the sticky element.
It’s height was not getting set because of a missing semicolon in the
shim element’s `style` attribute.
Position of elements are normally checked when you
scroll but we also need it to check when the page
loads.
Re-calculate element positions if window resizes.
Adds a flag to mark if all elements have a height
which will not change as their contents have
loaded.
