Save memory when StyleRule doesn't need nesting support

[mdubet]

9db1de4

Save memory when StyleRule doesn't need nesting support
https://bugs.webkit.org/show_bug.cgi?id=252176
rdar://105399781

Reviewed by Antti Koivisto.

Support for CSS Nesting has added 2 members to the StyleRule class
(the resolved selector list, and the list of children rules),
which created a memory regression of Membuster.

This patch creates a separate StyleWithNestingRule to be used when we actually
need the CSS Nesting feature (which is determined at parsing time).

When we don't need the CSS Nesting feature, it has exactly zero memory cost.

* Source/WebCore/bindings/js/JSCSSRuleCustom.cpp:
(WebCore::toJSNewlyCreated):
* Source/WebCore/css/CSSSelectorList.cpp:
(WebCore::CSSSelectorList::hasExplicitNestingParent const):
* Source/WebCore/css/CSSSelectorList.h:
* Source/WebCore/css/CSSStyleRule.cpp:
(WebCore::CSSStyleRule::CSSStyleRule):
(WebCore::CSSStyleRule::nestedRules const):
(WebCore::CSSStyleRule::cssText const):
(WebCore::CSSStyleRule::length const):
(WebCore::CSSStyleRule::item const):
* Source/WebCore/css/CSSStyleRule.h:
* Source/WebCore/css/StyleRule.cpp:
(WebCore::StyleRuleBase::visitDerived):
(WebCore::StyleRuleBase::createCSSOMWrapper const):
(WebCore::StyleRule::StyleRule):
(WebCore::StyleRule::create):
(WebCore::StyleRule::createForSplitting):
(WebCore::StyleRule::resolvedSelectorList const):
(WebCore::StyleRuleWithNesting::create):
(WebCore::StyleRuleWithNesting::StyleRuleWithNesting):
(WebCore::StyleRuleWithNesting::setResolvedSelectorList const):
(WebCore::StyleRuleGroup::StyleRuleGroup):
(WebCore::StyleRuleRareData::createIfNeeded): Deleted.
(WebCore::StyleRule::rareData const): Deleted.
(WebCore::StyleRule::setNestedRules): Deleted.
(WebCore::StyleRule::setResolvedSelectorList const): Deleted.
(WebCore::emptyRuleVector): Deleted.
(WebCore::StyleRule::nestedRules const): Deleted.
* Source/WebCore/css/StyleRule.h:
(WebCore::StyleRuleBase::isStyleRule const):
(WebCore::StyleRuleBase::isStyleRuleWithNesting const):
(WebCore::StyleRuleBase::setType):
(isType):
(WebCore::StyleRuleRareData::createIfNeeded): Deleted.
* Source/WebCore/css/StyleRuleType.h:
* Source/WebCore/css/StyleSheetContents.cpp:
(WebCore::StyleSheetContents::traverseSubresources const):
* Source/WebCore/css/parser/CSSParserImpl.cpp:
(WebCore::CSSParserImpl::createNestingParentRule):
(WebCore::CSSParserImpl::consumeStyleRule):
* Source/WebCore/css/parser/CSSParserImpl.h:
* Source/WebCore/inspector/InspectorStyleSheet.cpp:
(WebCore::flatteningStrategyForStyleRuleType):
* Source/WebCore/style/RuleSetBuilder.cpp:
(WebCore::Style::RuleSetBuilder::addChildRule):
(WebCore::Style::RuleSetBuilder::populateStyleRuleResolvedSelectorList):
(WebCore::Style::RuleSetBuilder::addStyleRuleWithSelectorList):
(WebCore::Style::RuleSetBuilder::addStyleRule):
* Source/WebCore/style/RuleSetBuilder.h:

Canonical link: https://commits.webkit.org/260281@main

77fd382

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

[webkit-early-warning-system]

EWS run on previous version of this PR (hash a9a9cab)

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

[webkit-early-warning-system]

EWS run on previous version of this PR (hash fe6ae41)

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

[webkit-early-warning-system]

EWS run on previous version of this PR (hash ed1cff4)

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

[webkit-early-warning-system]

EWS run on current version of this PR (hash 77fd382)

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

[webkit-commit-queue]

Committed 260281@main (9db1de4): https://commits.webkit.org/260281@main

Reviewed commits have been landed. Closing PR #10044 and removing active labels.