feat(@schematics/angular): move the reflect-metadata import to dev environment

It is not used in AOT with Angular. Only if you use a library that needs them.

Author: hansl

packages/schematics/angular/application/files/src/environments/environment.ts

@@ -2,6 +2,11 @@
 // `ng build --prod` replaces `environment.ts` with `environment.prod.ts`.
 // The list of file replacements can be found in `angular.json`.
 
+// Used for reflect-metadata in JIT. For size and performance reasons, this should not be imported
+// in AOT unless absolutely needed. All Angular metadata is removed in AOT so this is only needed,
+// by default, in development.
+import 'core-js/es7/reflect';
+
 export const environment = {
   production: false
 };

packages/schematics/angular/application/files/src/polyfills.ts

@@ -42,10 +42,6 @@
 
 
 /** Evergreen browsers require these. **/
-// Used for reflect-metadata in JIT. If you use AOT (and only Angular decorators), you can remove.
-import 'core-js/es7/reflect';
-
-
 /**
  * Web Animations `@angular/platform-browser/animations`
  * Only required if AnimationBuilder is used within the application and using IE/Edge or Safari.