Introduce a concrete result type for JSValue -> Implementation conversions

[weinig]

9a160ff

Introduce a concrete result type for JSValue -> Implementation conversions
https://bugs.webkit.org/show_bug.cgi?id=274682

Reviewed by Ryosuke Niwa.

Introduces "ConversionResult" a template type that serves as the return value
for all the JSValue -> Implementation conversion functions. It acts much like
ExceptionOr, is even implemented similarly on top of Expected, but instead of
storing either a result or the exception information, it stores the result or
a token indicating an exception exists on the JS stack.

The goal of this type is to allow conversions to non-default initializable
types, crucially, dictionaries and unions with Ref members. This introductory
change does not utilize that, but rather has deferred that to a follow up.

This change is mostly comprised of:

- Updating the code generator to handle the new return type.
- Updating JSDOM* converters to return the new type.
- Update non-generated uses of the convert<...> family of functions to handle
  the new result type.

* Source/WTF/wtf/TrailingArray.h:
(WTF::TrailingArray::TrailingArray):
    - Ensure the destructors don't run on the uninitialized elements when
      initializing trailing array's from a generator.

* Source/WebCore/Headers.cmake:
* Source/WebCore/WebCore.xcodeproj/project.pbxproj:
    - Add new files

* Source/WebCore/bindings/scripts/CodeGeneratorJS.pm:
    - Update code generation to handle new conversion result type.

* Source/WebCore/bindings/IDLTypes.h:
    - Add new trait types ConversionResultType and NullableConversionResultType
      to allow customization of the storage in ConversionResult for that type.

    - Also adds a new IDLOptional type that the generator uses to streamline
      optional arguments and optional dictionary members.

* Source/WebCore/bindings/js/JSDOMConvertResult.h: Added.
    - New result type.

* Source/WebCore/bindings/js/JSCallbackData.h:
    - Callback functions and interfaces now generate a JSDOMCallbackConverterTraits
      instance to allow generic mapping from the JS callback type to the implementation
      callback type.

* Source/WebCore/bindings/js/JSDOMConvertAny.h:
* Source/WebCore/bindings/js/JSDOMConvertBase.h:
* Source/WebCore/bindings/js/JSDOMConvertBoolean.h:
* Source/WebCore/bindings/js/JSDOMConvertBufferSource.h:
* Source/WebCore/bindings/js/JSDOMConvertCallbacks.h:
* Source/WebCore/bindings/js/JSDOMConvertDate.h:
* Source/WebCore/bindings/js/JSDOMConvertDictionary.h:
* Source/WebCore/bindings/js/JSDOMConvertEnumeration.h:
* Source/WebCore/bindings/js/JSDOMConvertEventListener.h:
* Source/WebCore/bindings/js/JSDOMConvertInterface.h:
* Source/WebCore/bindings/js/JSDOMConvertJSON.h:
* Source/WebCore/bindings/js/JSDOMConvertNull.h:
* Source/WebCore/bindings/js/JSDOMConvertNullable.h:
* Source/WebCore/bindings/js/JSDOMConvertNumbers.cpp:
* Source/WebCore/bindings/js/JSDOMConvertNumbers.h:
* Source/WebCore/bindings/js/JSDOMConvertObject.h:
* Source/WebCore/bindings/js/JSDOMConvertOptional.h:
* Source/WebCore/bindings/js/JSDOMConvertPromise.h:
* Source/WebCore/bindings/js/JSDOMConvertRecord.h:
* Source/WebCore/bindings/js/JSDOMConvertScheduledAction.h:
* Source/WebCore/bindings/js/JSDOMConvertSequences.h:
* Source/WebCore/bindings/js/JSDOMConvertSerializedScriptValue.h:
* Source/WebCore/bindings/js/JSDOMConvertXPathNSResolver.h:
* Source/WebCore/bindings/js/JSDOMConvertStrings.cpp:
* Source/WebCore/bindings/js/JSDOMConvertStrings.h:
    - Update to return new ConversionResult type.

    - Where there was a lot of unnecessary repetition, such as typed arrays,
      strings and numbers, intermediary converters were added to help reduce
      the overhead.

* Source/WebCore/bindings/js/JSDOMConvertUnion.h:
    - In addition to updating to the new result type, some simplification was
      done using constexpr to replace "Conditional*" meta-functions.

* Source/WebCore/bindings/js/JSDOMConvertVariadic.h:
    - Updated to use the recently introduced FixedVector::createWithSizeFromGenerator,
      which allows creation with non-default constructible arguments that can fail.

* Source/WebCore/Modules/applepay-ams-ui/ApplePayAMSUIPaymentHandler.cpp:
* Source/WebCore/Modules/applepay/paymentrequest/ApplePayPaymentHandler.cpp:
* Source/WebCore/Modules/mediastream/RTCPeerConnection.cpp:
* Source/WebCore/Modules/mediastream/RTCRtpSFrameTransform.cpp:
* Source/WebCore/Modules/mediastream/RTCRtpScriptTransformer.cpp:
* Source/WebCore/Modules/paymentrequest/PaymentRequest.cpp:
* Source/WebCore/Modules/permissions/Permissions.cpp:
* Source/WebCore/Modules/streams/TransformStream.cpp:
* Source/WebCore/Modules/webaudio/AudioWorkletGlobalScope.cpp:
* Source/WebCore/Modules/webtransport/DatagramSink.cpp:
* Source/WebCore/animation/KeyframeEffect.cpp:
* Source/WebCore/bindings/js/InternalReadableStream.cpp:
* Source/WebCore/bindings/js/JSCustomElementRegistryCustom.cpp:
* Source/WebCore/bindings/js/JSDOMWindowCustom.cpp:
* Source/WebCore/bindings/js/JSDocumentCustom.cpp:
* Source/WebCore/bindings/js/JSElementCustom.cpp:
* Source/WebCore/bindings/js/JSElementInternalsCustom.cpp:
* Source/WebCore/bindings/js/JSEventListener.cpp:
* Source/WebCore/bindings/js/JSExtendableMessageEventCustom.cpp:
* Source/WebCore/bindings/js/JSNodeIteratorCustom.cpp:
* Source/WebCore/bindings/js/JSRTCRtpSFrameTransformCustom.cpp:
* Source/WebCore/bindings/js/JSTreeWalkerCustom.cpp:
* Source/WebCore/bindings/js/JSWebAnimationCustom.cpp:
* Source/WebCore/crypto/SubtleCrypto.cpp:
* Source/WebCore/css/CSSStyleSheetObservableArray.cpp:
* Source/WebCore/html/HTMLCanvasElement.cpp:
* Source/WebCore/html/OffscreenCanvas.cpp:
* Source/WebCore/inspector/InspectorCanvas.cpp:
* Source/WebCore/inspector/InspectorCanvasCallTracer.h:
* Source/WebCore/worklets/PaintWorkletGlobalScope.cpp:
* Source/WebKit/WebProcess/Network/WebTransportSendStreamSink.cpp:
    - Update account for new result types.

Canonical link: https://commits.webkit.org/279321@main

c2de37b

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✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2	✅ 🧪 wincairo-tests
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	✅ 🛠 tv-sim	✅ 🧪 mac-wk2-stress	🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch		✅ 🛠 jsc-armv7
	✅ 🛠 watch-sim		❌ 🧪 jsc-armv7-tests

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

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❌ 🧪 style	🛠 ios	✅ 🛠 mac	🛠 wpe	🛠 wincairo
✅ 🧪 bindings	🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2	🧪 wincairo-tests
✅ 🧪 webkitperl	🧪 ios-wk2	⏳ 🧪 api-mac	🧪 api-wpe
	🧪 ios-wk2-wpt	🧪 mac-wk1	🛠 wpe-cairo
🛠 🧪 jsc	🧪 api-ios	🧪 mac-wk2	🛠 gtk
🛠 🧪 jsc-arm64	🛠 tv	⏳ 🧪 mac-AS-debug-wk2	🧪 gtk-wk2
	🛠 tv-sim	🧪 mac-wk2-stress	🧪 api-gtk
	🛠 watch		🛠 jsc-armv7
	🛠 watch-sim		🧪 jsc-armv7-tests

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❌ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	❌ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	❌ 🧪 wpe-wk2	🧪 wincairo-tests
✅ 🧪 webkitperl	🧪 ios-wk2	✅ 🧪 api-mac	❌ 🧪 api-wpe
	⏳ 🧪 ios-wk2-wpt	❌ 🧪 mac-wk1	❌ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	⏳ 🧪 api-ios	❌ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	❌ 🧪 mac-AS-debug-wk2	⏳ 🧪 gtk-wk2
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2-stress	⏳ 🧪 api-gtk
	✅ 🛠 watch		✅ 🛠 jsc-armv7
	✅ 🛠 watch-sim		❌ 🧪 jsc-armv7-tests

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✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	❌ 🧪 wpe-wk2	❌ 🧪 wincairo-tests
✅ 🧪 webkitperl	❌ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	❌ 🧪 mac-wk1	✅ 🛠 wpe-cairo
✅ 🛠 🧪 jsc	✅ 🧪 api-ios	❌ 🧪 mac-wk2	✅ 🛠 gtk
✅ 🛠 🧪 jsc-arm64	✅ 🛠 tv	❌ 🧪 mac-AS-debug-wk2	❌ 🧪 gtk-wk2
	✅ 🛠 tv-sim	✅ 🧪 mac-wk2-stress	❌ 🧪 api-gtk
	✅ 🛠 watch		✅ 🛠 jsc-armv7
	✅ 🛠 watch-sim		❌ 🧪 jsc-armv7-tests

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

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EWS run on previous version of this PR (hash 720aa32)

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

[webkit-early-warning-system]

EWS run on current version of this PR (hash c2de37b)

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

[webkit-commit-queue]

Committed 279321@main (9a160ff): https://commits.webkit.org/279321@main

Reviewed commits have been landed. Closing PR #29085 and removing active labels.