Add "parent widget" button to test property editor

Without this its hard to access the properties of container
widgets.

https://bugzilla.gnome.org/show_bug.cgi?id=687842
gdk: Add gdk_window_has_alpha helper

This centralizes the current checks for has_alpha_bg, which
lets us extend the check later.

https://bugzilla.gnome.org/show_bug.cgi?id=687842
Fix cnp bug in _gtk_bitmask_intersects

We need to use the allocated codepath if *any* argument is
allocated, not if one arg is not allocated.
This bug caused unnecessary calls to _gtk_bitmask_is_allocated,
as well as return completely wrong result if both bitmask are
allocated.
Exit early in gtk_style_context_update_cache codepaths

If lookup->missing is empty we don't need to continue looking.
We short circuit in several places as this can happen
after iteratively makeign lookup->missing smaller.
gtk_css_style_provider_lookup: minor loop optimiziation

This is a minor performance improvement but this loop
is run a lot so it actually matters in large state
changes.
Make _gtk_css_lookup_get_missing inline

This is called a lot in the loop in gtk_css_style_provider_lookup which
actually showed up on profiles.
icon-theme: Add some preconditions for NULL arguments

Related to this crash: https://bugzilla.gnome.org/show_bug.cgi?id=687967

https://bugzilla.gnome.org/show_bug.cgi?id=687977
Updated POTFILES.skip
reftests: Add a test for all the color names

BIG NOTE: We fail on some of these to give the colors defined in the CSS
specs. This is not good, but I'm not sure how to best fix it.
For those cases, I've kept the correct color in the CSS file but added
the correct one next to it.
cssvalue: Make shade() work properly again

In a previous commit, I accidentally scaled the hue instead of the
saturation. Ooops.
bitmask: Fix intersection code

With the fix in 77912a65e2aa6eb9cfee994fa93bbfbc6b9f8538, another bug
got visible: booleans are 32 bits, so if the intersection between the 2
bitmasks happened in higher bits, the return value would be truncated to
FALSE.

This actually made slider handles disappear, so it was pretty visible.
tests: Add some bitmasks to the hardcoded list

The bitmasks with the 31st, 32nd and 63rd bit set are added. The make up
the largest bitmasks on 32bit/64bit that can be represented without
allocating and the smallest bitmask on 32bit that must be allocated.
tests: Add an intersection test for the recent bug

Just using the hardcoded bitmasks triggered the bug fixed in commit
e8f2eeac9221d91ba32447bbcbdc5ba057647f8e - so just do that as the test.
Updated POTFILES.skip
bin: Only handle size for the child if it is visible
window: Remove useless functions

Now that GtkBin implements sizing functionality, there's no need to do
the same in GtkWindow
container: Simplify code

We will never get allocated a too small size, so no need to handle that
case.
bin: Handle border width if we have to

Some bin subclasses call gtk_container_handle_border_width(), some
don't. So work with both cases.
reftests: Add a test for border-width problems
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