Cherry-pick b7edb91. rdar://122431520

    Fix the DynamicContentScalingImageBufferBackend build
    https://bugs.webkit.org/show_bug.cgi?id=268867
    rdar://122431520

    Unreviewed build fix.

    * Source/WebKit/Shared/RemoteLayerTree/DynamicContentScalingImageBufferBackend.mm:
    (WebKit::DynamicContentScalingImageBufferBackend::createBackendHandle const):

    Canonical link: https://commits.webkit.org/274179@main

Identifier: 273664.405@safari-7619.1.3-branch

Source/WebKit/Shared/RemoteLayerTree/DynamicContentScalingImageBufferBackend.mm

@@ -89,7 +89,7 @@ static CFDictionaryRef makeContextOptions(const DynamicContentScalingImageBuffer
 {
 }
 
-std::optional<ImageBufferBackendHandle> DynamicContentScalingImageBufferBackend::createBackendHandle(SharedMemory::Protection) const
+std::optional<ImageBufferBackendHandle> DynamicContentScalingImageBufferBackend::createBackendHandle(WebCore::SharedMemory::Protection) const
 {
     if (!m_context)
         return std::nullopt;