Services overlay flashes a lot; should have some hysteresis before showing overlay

Services overlay flashes a lot; should have some hysteresis before showing overlay
https://bugs.webkit.org/show_bug.cgi?id=135683
<rdar://problem/16878039>

Reviewed by Simon Fraser.

Don't show the highlight until it's been 200ms since the last change
in selection or change in which highlight is hovered, whichever was more recent.

* WebProcess/WebPage/ServicesOverlayController.h:
* WebProcess/WebPage/mac/ServicesOverlayController.mm:
(WebKit::ServicesOverlayController::ServicesOverlayController):
(WebKit::ServicesOverlayController::selectionRectsDidChange):
Keep track of when the selection last changed.

(WebKit::ServicesOverlayController::drawTelephoneNumberHighlightIfVisible):
Make establishHoveredTelephoneHighlight take a bool instead of Boolean.

(WebKit::ServicesOverlayController::mouseIsOverHighlight):
Factor mouseIsOverHighlight out of establishHoveredTelephoneHighlight and drawHighlight.

(WebKit::ServicesOverlayController::remainingTimeUntilHighlightShouldBeShown):
Return the amount of time until the highlight should be shown; this is
the maximum of (the difference between the last selection change and the timeout)
and (the difference between the last change in which highlight is hovered and the timeout).

Telephone number highlights are shown immediately, because they are already stable
by virtue of being expanded to include the entire telephone number.

(WebKit::ServicesOverlayController::repaintHighlightTimerFired):
(WebKit::ServicesOverlayController::drawHighlight):
If the highlight shouldn't be shown yet (because we haven't hit the two timeouts),
schedule a timer to repaint us around when we will hit the timeouts.

(WebKit::ServicesOverlayController::establishHoveredTelephoneHighlight):
(WebKit::ServicesOverlayController::mouseEvent):
Don't allow mouseUp to trigger the menu if we shouldn't be showing the overlay yet.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@172200 268f45cc-cd09-0410-ab3c-d52691b4dbfc