fix: include content in css sourcemap when extracting (#1627)

Co-authored-by: Adam Skoufis <[email protected]>

Author: stipsan

.changeset/breezy-poets-matter.md

@@ -0,0 +1,5 @@
+---
+'@vanilla-extract/rollup-plugin': patch
+---
+
+Include content in CSS sourcemap when bundling with the `extract` option

packages/rollup-plugin/src/index.ts

@@ -174,7 +174,9 @@ export function vanillaExtractPlugin({
           type: 'asset',
           name: sourcemapName,
           originalFileName: sourcemapName,
-          source: bundle.generateMap({ file: name }).toString(),
+          source: bundle
+            .generateMap({ file: name, includeContent: true })
+            .toString(),
         });
       }
     },