Fix declaration emit crash (#58872)

src/services/utilities.ts

@@ -2408,15 +2408,6 @@ export function isTypeKeywordTokenOrIdentifier(node: Node) {
     return isTypeKeywordToken(node) || isIdentifier(node) && node.text === "type";
 }
 
-/**
- * True if the symbol is for an external module, as opposed to a namespace.
- *
- * @internal
- */
-export function isExternalModuleSymbol(moduleSymbol: Symbol): boolean {
-    return !!(moduleSymbol.flags & SymbolFlags.Module) && moduleSymbol.name.charCodeAt(0) === CharacterCodes.doubleQuote;
-}
-
 /**
  * Returns `true` the first time it encounters a node and `false` afterwards.
  *