Remove @internal from Program::isSourceFileDefaultLibrary

Fixes microsoft#25225

Author: timocov

src/compiler/types.ts

@@ -2774,7 +2774,7 @@ namespace ts {
         /* @internal */ getFileProcessingDiagnostics(): DiagnosticCollection;
         /* @internal */ getResolvedTypeReferenceDirectives(): Map<ResolvedTypeReferenceDirective>;
         isSourceFileFromExternalLibrary(file: SourceFile): boolean;
-        /* @internal */ isSourceFileDefaultLibrary(file: SourceFile): boolean;
+        isSourceFileDefaultLibrary(file: SourceFile): boolean;
 
         // For testing purposes only.
         /* @internal */ structureIsReused?: StructureIsReused;

tests/baselines/reference/api/typescript.d.ts

@@ -1780,6 +1780,7 @@ declare namespace ts {
          */
         getTypeChecker(): TypeChecker;
         isSourceFileFromExternalLibrary(file: SourceFile): boolean;
+        isSourceFileDefaultLibrary(file: SourceFile): boolean;
         getProjectReferences(): (ResolvedProjectReference | undefined)[] | undefined;
     }
     interface ResolvedProjectReference {