Bug 283847 – [macOS] Spurious ASSERT fails under WebCore::DictionaryLookup::stringForPDFSelection with empty selection

• Status: RESOLVED
• Resolution: FIXED
• Component: PDF

[Abrar Rahman Protyasha]

rdar://128668294

[Abrar Rahman Protyasha]

The selection string check assert in `DictionaryLookup::stringForPDFSelection()` fails unexpectedly, sometimes, with this signature:

```
Thread 0 Crashed::   Dispatch queue: com.apple.main-thread
0   com.apple.WebCore             	       0x14d57f0ac WTFCrashWithInfo(int, char const*, char const*, int)
1   com.apple.WebCore             	       0x14b559ae8 WebCore::DictionaryLookup::stringForPDFSelection(PDFSelection*)
2   com.apple.WebKit              	       0x1163e5c50 WebKit::UnifiedPDFPlugin::textForImmediateActionHitTestAtPoint(WebCore::FloatPoint const&, WebKit::WebHitTestResultData&)
3   com.apple.WebKit              	       0x11635cc8c WebKit::PDFPluginBase::performImmediateActionHitTestAtLocation(WebCore::FloatPoint const&, WebKit::WebHitTestResultData&)
4   com.apple.WebKit              	       0x11701156c WebKit::PluginView::performImmediateActionHitTestAtLocation(WebCore::FloatPoint const&, WebKit::WebHitTestResultData&) const
5   com.apple.WebKit              	       0x116701994 WebKit::WebPage::performImmediateActionHitTestAtLocation(WebCore::ProcessQualified<WTF::ObjectIdentifierGeneric<WebCore::FrameIdentifierType, WTF::ObjectIdentifierMainThreadAccessTraits>>, WebCore::FloatPoint)
```

Kimmo was able to reliably reproduce this assert with the following reproduction steps:

1. https://developer.apple.com/metal/Metal-Shading-Language-Specification.pdf
3. Click a link in "Contents", hit the place where there is multiple dots ".........."

[Abrar Rahman Protyasha]

Pull request: https://github.com/WebKit/WebKit/pull/37306

[EWS]

Committed 287236@main (16048339c64a): <https://commits.webkit.org/287236@main>

Reviewed commits have been landed. Closing PR #37306 and removing active labels.