[iOS WK2] Remove _WKDraggableElementInfo and fold PositionInformationTests into WKReq...

[iOS WK2] Remove _WKDraggableElementInfo and fold PositionInformationTests into WKRequestActivatedElementInfo
https://bugs.webkit.org/show_bug.cgi?id=174758

Reviewed by Dan Bernstein.

Source/WebKit:

_WKDraggableElementInfo is no longer used in WebKit, so it should be removed. However, some of the scenarios
in PositionInformationTests that depend on _WKDraggableElementInfo are still useful to exercise: namely,
performing both synchronous and asynchronous position information updates while an async position information
update is in flight. This patch refactors these unit tests into 2 new unit tests in the existing
WKRequestActivatedElementInfo test suite.

* UIProcess/API/Cocoa/WKWebView.mm:
(-[WKWebView _draggableElementAtPosition:]): Deleted.
(-[WKWebView _requestDraggableElementAtPosition:completionBlock:]): Deleted.
* UIProcess/API/Cocoa/WKWebViewPrivate.h:
* UIProcess/API/Cocoa/_WKDraggableElementInfo.h: Removed.
* UIProcess/API/Cocoa/_WKDraggableElementInfo.mm: Removed.
* UIProcess/API/Cocoa/_WKDraggableElementInfoInternal.h: Removed.
* UIProcess/ios/WKContentViewInteraction.mm:
* WebKit.xcodeproj/project.pbxproj:

Tools:

Migrate position-information-related unit tests from the PositionInformationTests suite to
WKRequestActivatedElementInfo as 2 new unit tests. See WebKit2 ChangeLog for more details.

* TestWebKitAPI/TestWebKitAPI.xcodeproj/project.pbxproj:
* TestWebKitAPI/Tests/WebKit2Cocoa/WKRequestActivatedElementInfo.mm:
(TestWebKitAPI::checkElementTypeAndBoundingRect):
(TestWebKitAPI::TEST):
* TestWebKitAPI/Tests/ios/PositionInformationTests.mm: Removed.
* TestWebKitAPI/cocoa/TestWKWebView.h:
* TestWebKitAPI/cocoa/TestWKWebView.mm:
(-[TestWKWebView activatedElementAtPosition:]):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@219768 268f45cc-cd09-0410-ab3c-d52691b4dbfc