chore(type): remove unnecessary type assertion (#4150)

Author: webfansplz

packages/compiler-sfc/src/compileStyle.ts

@@ -186,7 +186,7 @@ export function doCompileStyle(
       return result
         .then(result => ({
           code: result.css || '',
-          map: result.map && (result.map.toJSON() as any),
+          map: result.map && result.map.toJSON(),
           errors,
           modules: cssModules,
           rawResult: result,
@@ -211,7 +211,7 @@ export function doCompileStyle(
 
   return {
     code: code || ``,
-    map: outMap && (outMap.toJSON() as any),
+    map: outMap && outMap.toJSON(),
     errors,
     rawResult: result,
     dependencies