[gtk/gtk-3-24] (20 commits) ...Merge branch 'quartz-monitor' into gtk-3-24

[John Ralls <jralls src gnome org>]

Summary of changes:

  2b1c3fb... Reorder virtual method assignments and fill in missing ones
  74aecac... Remove commented-out code copied from X11 implementation.
  4d0cae4... Replace convertBaseToScreen & convertScreenToBase.
  6ac8154... Prevent crash from passing NULL style provider.
  cf279a1... Don't attempt to dereference icon_theme until after checkin
  28b8bbd... Implement the GdkMonitor/GdkDisplay API.
  08b871f... Replace the deprecated GdkDisplayManager with GdkSeat.
  85f52dc... Replace NSInputManager for MacOS 10.6 and later.
  9773b19... Clean up some unused variables.
  941f3c3... Move the CGDisplayReconfigurationCallback to gdkdisplay-qua
  f30ed5d... Fix Cocoa style and event constants for MacOS X 10.12 and l
  ca6db9a... Add compile-time check for NSGraphicsContext graphicsPort/C
  1165ab9... Replace deprecated gestalt for 10.10 and later.
  eb2799c... Make _gdk_quartz_window_flush a no-op for MacOS 10.14 and l
  89c8c55... Remove 2 unused functions.
  e786da9... Complete GdkQuartzDisplay Implementation.
  5294c4f... Fix crash if there are no grabs in place.
  9e212cd... Prevent crash if display->touch_implicit_grabs is NULL.
  833ddc6... Silence enum type warning in 10.9.
  46bee8b... Merge branch 'quartz-monitor' into gtk-3-24