fix(@angular-devkit/build-angular): load style source maps inline so they work

without this, the way styles are into the DOM breaks the default sourcemap option
postcss-loader option docs
https://github.com/postcss/postcss-loader#inline
fixes #9099

Author: ajspera

packages/angular_devkit/build_angular/src/angular-cli-files/models/webpack-configs/styles.ts

@@ -244,7 +244,7 @@ export function getStylesConfig(wco: WebpackConfigOptions) {
         options: {
           ident: 'embedded',
           plugins: postcssPluginCreator,
-          sourceMap: cssSourceMap
+          sourceMap: cssSourceMap ? 'inline' : false
         }
       },
       ...(use as webpack.Loader[])
@@ -267,7 +267,7 @@ export function getStylesConfig(wco: WebpackConfigOptions) {
             options: {
               ident: buildOptions.extractCss ? 'extracted' : 'embedded',
               plugins: postcssPluginCreator,
-              sourceMap: cssSourceMap
+              sourceMap: cssSourceMap && !buildOptions.extractCss ? 'inline' : cssSourceMap
             }
           },
           ...(use as webpack.Loader[])
@@ -300,6 +300,8 @@ export function getStylesConfig(wco: WebpackConfigOptions) {
   }
 
   return {
+    // Workaround stylus-loader defect: https://github.com/shama/stylus-loader/issues/189
+    loader: { stylus: {} },
     entry: entryPoints,
     module: { rules },
     plugins: [].concat(extraPlugins as any)