https://bugs.webkit.org/show_bug.cgi?id=34371

Reviewed by Simon Fraser.

WebCore: 

Allow ScrollbarTheme to cap the overlap between pages, and set a cap of
40 in ScrollbarThemeMac.

* WebCore.base.exp: Export Scrollbar::maxOverlapBetweenPages().
* editing/EditorCommand.cpp:
(WebCore::verticalScrollDistance): Use Scrollbar methods instead of
constants, and cap the scroll distance if needed.
* platform/ScrollView.cpp:
(WebCore::ScrollView::updateScrollbars): Ditto.
(WebCore::ScrollView::wheelEvent): Ditto.
* platform/Scrollbar.cpp:
(WebCore::Scrollbar::maxOverlapBetweenPages): Added. Returns the
value from the native scrollbar theme.
* platform/Scrollbar.h: Replaced scroll amount constants with static methods.
(WebCore::Scrollbar::pixelsPerLineStep): Replaces cScrollbarPixelsPerLineStep.
(WebCore::Scrollbar::minFractionToStepWhenPaging): Replaces cFractionToStepWhenPaging.
* platform/ScrollbarTheme.h:
(WebCore::ScrollbarTheme::maxOverlapBetweenPages): A base implementation
that returns the largest int.
* platform/gtk/WheelEventGtk.cpp:
(WebCore::PlatformWheelEvent::PlatformWheelEvent): Use Scrollbar methods instead of
constants.
* platform/haiku/PlatformWheelEventHaiku.cpp:
(WebCore::PlatformWheelEvent::PlatformWheelEvent): Use Scrollbar methods instead of
constants.
* platform/mac/ScrollbarThemeMac.h:
(WebCore::ScrollbarThemeMac::maxOverlapBetweenPages): An override
that returns 40.
* platform/mac/WheelEventMac.mm:
(WebCore::PlatformWheelEvent::PlatformWheelEvent): Use
Scrollbar::pixelsPerLineStep() instead of cScrollbarPixelsPerLineStep.
* platform/wx/MouseWheelEventWx.cpp:
(WebCore::PlatformWheelEvent::PlatformWheelEvent): Use Scrollbar methods instead of
constants.
* platform/wx/ScrollViewWx.cpp:
(WebCore::ScrollView::ScrollViewPrivate::OnScrollWinEvents): Use Scrollbar
methods instead of constants, and cap the scroll distance if needed.
* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::updateScrollInfoAfterLayout): Ditto.

WebKit/mac: 

* WebView/WebFrameView.mm:
(-[WebFrameView _verticalPageScrollDistance]): Use Scrollbar methods instead of
constants, and cap the scroll distance.
(-[WebFrameView initWithFrame:]): Use Scrollbar::pixelsPerLineStep() instead of
cScrollbarPixelsPerLineStep.
(-[WebFrameView _horizontalPageScrollDistance]):Use Scrollbar methods instead of
constants, and cap the scroll distance.

WebKit/wx: 

* WebView.cpp:
(wxWebView::OnKeyEvents): Use Scrollbar method instead of constant.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@54345 268f45cc-cd09-0410-ab3c-d52691b4dbfc