Expose isSourceFileFromExternalLibrary (#16112)

Author: ajafff

src/compiler/types.ts

@@ -2431,7 +2431,7 @@ namespace ts {
         getDeclarationDiagnostics(sourceFile?: SourceFile, cancellationToken?: CancellationToken): Diagnostic[];
 
         /**
-         * Gets a type checker that can be used to semantically analyze source fils in the program.
+         * Gets a type checker that can be used to semantically analyze source files in the program.
          */
         getTypeChecker(): TypeChecker;
 
@@ -2451,7 +2451,7 @@ namespace ts {
 
         /* @internal */ getFileProcessingDiagnostics(): DiagnosticCollection;
         /* @internal */ getResolvedTypeReferenceDirectives(): Map<ResolvedTypeReferenceDirective>;
-        /* @internal */ isSourceFileFromExternalLibrary(file: SourceFile): boolean;
+        isSourceFileFromExternalLibrary(file: SourceFile): boolean;
         // For testing purposes only.
         /* @internal */ structureIsReused?: StructureIsReused;