perf(@angular-devkit/build-angular): conditionally add Angular compil…

…er plugin to polyfills bundling

When using the esbuild-based builders (`application`/`browser-esbuild`), the Angular compiler plugin
is now only added to the polyfills bundler configuration if TypeScript files are found in the `polyfills`
build option. This is not the case for a default project. The Angular compiler plugin is used to provide
type-checking diagnostics for any TypeScript files present within the build. However, if there are no
TypeScript files to process, there is no need to use it for the polyfills processing.

packages/angular_devkit/build_angular/src/tools/esbuild/application-code-bundle.ts

@@ -86,12 +86,7 @@ export function createBrowserPolyfillBundleOptions(
     return;
   }
 
-  const { outputNames } = options;
-  const { pluginOptions, styleOptions } = createCompilerPluginOptions(
-    options,
-    target,
-    sourceFileCache,
-  );
+  const { outputNames, polyfills } = options;
 
   const buildOptions: BuildOptions = {
     ...polyfillBundleOptions,
@@ -108,15 +103,24 @@ export function createBrowserPolyfillBundleOptions(
     },
   };
 
-  buildOptions.plugins ??= [];
-  buildOptions.plugins.push(
-    createCompilerPlugin(
-      // JS/TS options
-      { ...pluginOptions, noopTypeScriptCompilation: true },
-      // Component stylesheet options are unused for polyfills but required by the plugin
-      styleOptions,
-    ),
-  );
+  // Only add the Angular TypeScript compiler if TypeScript files are provided in the polyfills
+  const hasTypeScriptEntries = polyfills?.some((entry) => /\.[cm]?tsx?$/.test(entry));
+  if (hasTypeScriptEntries) {
+    buildOptions.plugins ??= [];
+    const { pluginOptions, styleOptions } = createCompilerPluginOptions(
+      options,
+      target,
+      sourceFileCache,
+    );
+    buildOptions.plugins.push(
+      createCompilerPlugin(
+        // JS/TS options
+        { ...pluginOptions, noopTypeScriptCompilation: true },
+        // Component stylesheet options are unused for polyfills but required by the plugin
+        styleOptions,
+      ),
+    );
+  }
 
   return buildOptions;
 }