Add a fast path for parent selector matching that uses a bloom filter to
quickly discard selectors that can't possibly match.
Keep in mind that we match using a bloom filter, so we might
accidentally include too many selectors when hash/bucket collisions
occur.
That's not a correctness problem though, because we'll do a real check
afterwards.
The idea for this change is taken from browsers, in particular WebKit.
The reason for this is simply that I want to get hash functions that
have their values close together, so they can fit in a smaller range
(the goal here is 12 bits). By using GQuark, we get consecutive numbers
starting with 1 (and applications have <1000 quarks usually), whereas
interned strings can be all over the place.
As a side effect we also save 64 bytes per declaration.
The function was not selector-specific, so putting it with all the other
utility functions makes more sense.
Also use the utility function in the node declaration printing.
The node declaration has all the information we are printing
here (except for visibility). At the same time, redo the format
to print the information in selector format, and indicate
(in)visibility by enclosing the selector in square brackets.
The widget path machinery assumes that we always have types,
and without this change, it will start spewing warnings when
we start to introduce node names.
The previous code was crashing when used as the returned classes array
would have been invalid after the first deletion. So if a 2nd class
would be deleted, invalid memory might have been referenced.
This function is getting called a lot. Statistics for the gtk3-demo
listbox example show most calls with 0-4 classes. Unrolling the cases
a bit brings the instruction count in callgrind from 93M to 52M.
GtkCssNodeDeclaration is a new struct with copy-on-write semantics.
It encapsulated the properties used to define a node in the CSS tree.
The idea is to use it in various places for caching, in particular as
key in hash tables.
