Begin implementing back/forward cache for site isolation

[achristensen07]

00dcbd8

Begin implementing back/forward cache for site isolation
https://bugs.webkit.org/show_bug.cgi?id=265561
rdar://118965412

Reviewed by Pascoe.

My approach before was to terminate the iframe processes when we navigate away,
which seems to match other browsers but doesn't match our existing behavior of
being able to quickly navigate back to a fully functional page.  We need to keep
the processes alive and make CachedFrame able to handle RemoteFrames in order to
keep that speed.  If we get a memory pressure warning, we will remove back/forward
cache entries, but if we have the memory let's keep the existing behavior.

This is the first of at least two PRs to get back/forward navigation working with
site isolation.  I make CachedFrame able to handle RemoteFrames, I made
HistoryController a non-nested class to be able to be owned by RemoteFrames (but
I didn't change that ownership yet), and I swap RemotePageProxy state to a
SuspendedPageProxy when suspending.

* Source/WebCore/dom/Document.cpp:
(WebCore::Document::attachToCachedFrame):
* Source/WebCore/history/CachedFrame.cpp:
(WebCore::CachedFrameBase::CachedFrameBase):
(WebCore::CachedFrameBase::restore):
(WebCore::CachedFrame::CachedFrame):
(WebCore::CachedFrame::open):
(WebCore::CachedFrame::destroy):
* Source/WebCore/history/CachedFrame.h:
(WebCore::CachedFrameBase::view const):
* Source/WebCore/history/CachedPage.cpp:
(WebCore::CachedPage::CachedPage):
(WebCore::firePageShowEvent):
(WebCore::CachedPage::restore):
* Source/WebCore/loader/FrameLoader.cpp:
(WebCore::FrameLoader::open):
* Source/WebKit/UIProcess/SuspendedPageProxy.cpp:
(WebKit::SuspendedPageProxy::SuspendedPageProxy):
* Source/WebKit/UIProcess/WebFrameProxy.cpp:
(WebKit::WebFrameProxy::removeRemotePagesForSuspension): Deleted.
* Source/WebKit/UIProcess/WebFrameProxy.h:
* Tools/TestWebKitAPI/Tests/WebKitCocoa/SiteIsolation.mm:
(TestWebKitAPI::TEST):

Canonical link: https://commits.webkit.org/271590@main

b4b3d1e

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim
	✅ 🛠 watch
✅ 🛠 🧪 unsafe-merge	🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash ab75d5c)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	❌ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	❌ 🛠 ios-sim	❌ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	❌ 🧪 api-mac	✅ 🧪 api-wpe
	❌ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
	❌ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	❌ 🛠 tv	❌ 🧪 mac-AS-debug-wk2	❌ 🧪 api-gtk
	❌ 🛠 tv-sim
	❌ 🛠 watch
	❌ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 4bdab2f)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	❌ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	⏳ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	⏳ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	🧪 api-mac	✅ 🧪 api-wpe
	⏳ 🧪 ios-wk2-wpt	🧪 mac-wk1	✅ 🛠 gtk
⏳ 🛠 🧪 jsc	✅ 🧪 api-ios	🧪 mac-wk2	🧪 gtk-wk2
⏳ 🛠 🧪 jsc-arm64	⏳ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	⏳ 🧪 api-gtk
	✅ 🛠 tv-sim
	⏳ 🛠 watch
	⏳ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 031e044)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	🛠 ios	⏳ 🛠 mac	⏳ 🛠 wpe	⏳ 🛠 wincairo
✅ 🧪 bindings	⏳ 🛠 ios-sim	⏳ 🛠 mac-AS-debug	⏳ 🧪 wpe-wk2
✅ 🧪 webkitperl	⏳ 🧪 ios-wk2	⏳ 🧪 api-mac	⏳ 🧪 api-wpe
	⏳ 🧪 ios-wk2-wpt	⏳ 🧪 mac-wk1	⏳ 🛠 gtk
⏳ 🛠 🧪 jsc	⏳ 🧪 api-ios	⏳ 🧪 mac-wk2	⏳ 🧪 gtk-wk2
⏳ 🛠 🧪 jsc-arm64	⏳ 🛠 tv	⏳ 🧪 mac-AS-debug-wk2	⏳ 🧪 api-gtk
	⏳ 🛠 tv-sim	⏳ 🧪 mac-wk2-stress	⏳ 🛠 jsc-armv7
	⏳ 🛠 watch		⏳ 🧪 jsc-armv7-tests
	⏳ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 4152719)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	❌ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	⏳ 🛠 wincairo
✅ 🧪 bindings	❌ 🛠 ios-sim	✅ 🛠 mac-AS-debug	⏳ 🧪 wpe-wk2
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	⏳ 🧪 api-mac	✅ 🧪 api-wpe
	❌ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
⏳ 🛠 🧪 jsc	❌ 🧪 api-ios	⏳ 🧪 mac-wk2	🧪 gtk-wk2
⏳ 🛠 🧪 jsc-arm64	⏳ 🛠 tv	⏳ 🧪 mac-AS-debug-wk2	⏳ 🧪 api-gtk
	🛠 tv-sim
	⏳ 🛠 watch
	⏳ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash b4b3d1e)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv-sim
	✅ 🛠 watch
✅ 🛠 🧪 unsafe-merge	🛠 watch-sim

[webkit-commit-queue]

Committed 271590@main (00dcbd8): https://commits.webkit.org/271590@main

Reviewed commits have been landed. Closing PR #21092 and removing active labels.