[Mac] Upstream AppKit-related WebKitSystemInterface functions

[Mac] Upstream AppKit-related WebKitSystemInterface functions
https://bugs.webkit.org/show_bug.cgi?id=176175

Reviewed by Brady Eidson.

Source/WebCore:

* Configurations/WebCore.xcconfig: Added -ObjC to OTHER_LDFLAGS so that Objective-C classes
in PAL are exported by WebCore even if WebCore doesn't use them.
* platform/mac/PlatformEventFactoryMac.h:
* platform/mac/PlatformEventFactoryMac.mm:
(WebCore::getWheelEventDeltas):
(WebCore::keyCharForEvent):
(WebCore::PlatformWheelEventBuilder::PlatformWheelEventBuilder):
* platform/mac/WebCoreSystemInterface.h:
* platform/mac/WebCoreSystemInterface.mm:

Source/WebCore/PAL:

* PAL.xcodeproj/project.pbxproj:
* pal/spi/mac/HIToolboxSPI.h:
* pal/spi/mac/NSResponderSPI.h: Copied from Source/WebCore/PAL/pal/spi/mac/NSWindowSPI.h.
* pal/spi/mac/NSWindowSPI.h:
* pal/system/mac/WebPanel.h: Copied from Source/WebCore/PAL/pal/spi/mac/NSWindowSPI.h.
* pal/system/mac/WebPanel.mm: Copied from Source/WebCore/PAL/pal/spi/mac/HIToolboxSPI.h.
(-[WebPanel init]):

Source/WebKit:

* PluginProcess/mac/PluginProcessMac.mm:
(WebKit::initializeCocoaOverrides):
* Shared/mac/WebEventFactory.mm:
(WebKit::WebEventFactory::createWebWheelEvent):
(WebKit::WebEventFactory::createWebKeyboardEvent):
* UIProcess/mac/WKTextInputWindowController.mm:
(-[WKTextInputPanel init]):
* WebProcess/WebCoreSupport/mac/WebSystemInterface.mm:
(InitWebCoreSystemInterface):

Source/WebKitLegacy/mac:

* Plugins/Hosted/NetscapePluginInstanceProxy.mm:
(WebKit::NetscapePluginInstanceProxy::keyEvent):
* Plugins/Hosted/WebTextInputWindowController.m:
(-[WebTextInputPanel init]):
* WebCoreSupport/WebSystemInterface.mm:
(InitWebCoreSystemInterface):
* WebView/WebDynamicScrollBarsView.mm:
(-[WebDynamicScrollBarsView scrollWheel:]):
* WebView/WebHTMLView.mm:
(-[WebHTMLView _removeWindowObservers]):
(-[WebHTMLView addWindowObservers]):
* WebView/WebView.mm:
(-[WebView addWindowObserversForWindow:]):
(-[WebView removeWindowObservers]):
(-[WebView viewWillMoveToWindow:]):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@221473 268f45cc-cd09-0410-ab3c-d52691b4dbfc