Narrow return type of Performance/PerformanceObserverEntryList.getEntriesByType by entry type literal

[Copilot]

getEntriesByType was typed to always return PerformanceEntryList (PerformanceEntry[]), even though the runtime result is always a specific PerformanceEntry subclass determined by the type argument. This forced casts or caused false TS2339 errors, e.g. performance.getEntriesByType('navigation').some(e => e.type === 'reload') failed because type doesn't exist on PerformanceEntry.

Changes

• lib.dom.d.ts: Added literal-string overloads to getEntriesByType on both Performance and PerformanceObserverEntryList, mapping each known entry type to its concrete subclass, with the existing string overload retained as a fallback for unknown types:
  • "navigation" → PerformanceNavigationTiming[]
  • "resource" → PerformanceResourceTiming[]
  • "mark" → PerformanceMark[]
  • "measure" → PerformanceMeasure[]
  • "paint" → PerformancePaintTiming[]
  • "event" → PerformanceEventTiming[]
  • "largest-contentful-paint" → LargestContentfulPaint[]
• lib.webworker.d.ts: Added the matching overload subset ("mark", "measure", "resource") since only those subclasses exist in the worker global scope.
• Test: Added performanceGetEntriesByType.ts compiler test covering each overload and the generic fallback case.

function pageWasReloaded(): boolean {
    return performance
        .getEntriesByType('navigation') // now PerformanceNavigationTiming[]
        .some(entry => entry.type === 'reload'); // no longer an error
}

• Fixes TS 5.4.5: Return type for performance.getEntriesByType is inaccurate #58644