add languageVariant to SourceFileLike

Author: gabritto

src/compiler/types.ts

@@ -4288,6 +4288,7 @@ export interface SourceFileLike {
     lineMap?: readonly number[];
     /** @internal */
     getPositionOfLineAndCharacter?(line: number, character: number, allowEdits?: true): number;
+    languageVariant?: LanguageVariant;
 }
 
 /** @internal */

src/services/services.ts

@@ -504,7 +504,7 @@ function createChildren(node: Node, sourceFile: SourceFileLike | undefined): rea
         });
         return children;
     }
-    const languageVariant = (sourceFile as SourceFile)?.languageVariant ?? LanguageVariant.Standard;
+    const languageVariant = sourceFile?.languageVariant ?? LanguageVariant.Standard;
     scanner.setText((sourceFile || node.getSourceFile()).text);
     scanner.setLanguageVariant(languageVariant);
     let pos = node.pos;

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

@@ -5907,6 +5907,7 @@ declare namespace ts {
      */
     interface SourceFileLike {
         readonly text: string;
+        languageVariant?: LanguageVariant;
     }
     interface SourceFileLike {
         getLineAndCharacterOfPosition(pos: number): LineAndCharacter;