Bug 1496830 - Annotate CompositorHitTestFlags enumerators with the value they contribute to an EnumSet. r=kats

Differential Revision: https://phabricator.services.mozilla.com/D7920

--HG--
extra : moz-landing-system : lando

gfx/src/CompositorHitTestInfo.h

@@ -18,35 +18,37 @@ namespace gfx {
 // intentionally set up so that if all of them are 0 the item is effectively
 // invisible to hit-testing, and no information for this frame needs to be
 // sent to the compositor.
+// Each enumerator is annotated with the value it contributes to an
+// EnumSet (2 ^ <value of enumerator>), in hexadecimal.
 enum class CompositorHitTestFlags : uint8_t {
   // The frame participates in hit-testing
-  eVisibleToHitTest = 0,
+  eVisibleToHitTest = 0,              // 0x001
   // The frame requires main-thread handling for events
-  eDispatchToContent,
+  eDispatchToContent,                 // 0x002
 
   // The touch action flags are set up so that the default of
   // touch-action:auto on an element leaves all the flags as 0.
-  eTouchActionPanXDisabled,
-  eTouchActionPanYDisabled,
-  eTouchActionPinchZoomDisabled,
-  eTouchActionDoubleTapZoomDisabled,
+  eTouchActionPanXDisabled,           // 0x004
+  eTouchActionPanYDisabled,           // 0x008
+  eTouchActionPinchZoomDisabled,      // 0x010
+  eTouchActionDoubleTapZoomDisabled,  // 0x020
 
   // The frame is a scrollbar or a subframe inside a scrollbar (including
   // scroll thumbs)
-  eScrollbar,
+  eScrollbar,                         // 0x040
   // The frame is a scrollthumb. If this is set then eScrollbar will also be
   // set, unless gecko somehow generates a scroll thumb without a containing
   // scrollbar.
-  eScrollbarThumb,
+  eScrollbarThumb,                    // 0x080
   // If eScrollbar is set, this flag indicates if the scrollbar is a vertical
   // one (if set) or a horizontal one (if not set)
-  eScrollbarVertical,
+  eScrollbarVertical,                 // 0x100
 
   // Events targeting this frame should only be processed if a target
   // confirmation is received from the main thread. If no such confirmation
   // is received within a timeout period, the event may be dropped.
   // Only meaningful in combination with eDispatchToContent.
-  eRequiresTargetConfirmation,
+  eRequiresTargetConfirmation,        // 0x200
 };
 
 using CompositorHitTestInfo = EnumSet<CompositorHitTestFlags, uint32_t>;