fix(@angular-devkit/build-angular): resolve partial SCSS files in sourcemaps

Closes #19505

Author: alan-agius4

packages/angular_devkit/build_angular/src/browser/specs/source-map_spec.ts

@@ -158,4 +158,20 @@ describe('Browser Builder source map', () => {
     expect(await files['styles.css']).not.toContain('sourceMappingURL=styles.css.map');
     expect(await files['styles.css']).not.toContain('sourceMappingURL=data:application/json');
   });
+
+  it('should resolve sources to partial SCSS files', async () => {
+    const overrides = {
+      sourceMap: true,
+      extractCss: true,
+      styles: ['src/styles.scss'],
+    };
+
+    host.writeMultipleFiles({
+      'src/styles.scss': `@import './partial';`,
+      'src/_partial.scss': `p { color: red; }`,
+    });
+
+    const { files } = await browserBuild(architect, host, target, overrides);
+    expect(await files['styles.css.map']).toContain('_partial.scss');
+  });
 });

packages/angular_devkit/build_angular/src/webpack/configs/styles.ts

@@ -221,9 +221,7 @@ export function getStylesConfig(wco: WebpackConfigOptions) {
 
   // load global css as css files
   if (globalStylePaths.length > 0) {
-    const globalSourceMap = !!(
-      cssSourceMap && !buildOptions.extractCss && !buildOptions.sourceMap.hidden
-    );
+    const globalSourceMap = !!cssSourceMap && !buildOptions.sourceMap.hidden;
 
     rules.push(
       ...baseRules.map(({ test, use }) => {