Call Closure directly from Wireit (webcomponents#555)

Author: justinfagnani

packages/scoped-custom-element-registry/closure-flags.txt

@@ -0,0 +1,17 @@
+--compilation_level=ADVANCED_OPTIMIZATIONS
+--warning_level=VERBOSE
+--language_in=STABLE
+--language_out=ECMASCRIPT5_STRICT
+--dependency_mode=PRUNE
+--entry_point=./src/scoped-custom-element-registry.js
+--js=./src/scoped-custom-element-registry.js
+--js_output_file=./scoped-custom-element-registry.min.js
+--output_wrapper="(function(){
+%output%
+}).call(typeof globalThis === 'object' ? globalThis : window);
+
+//# sourceMappingURL=scoped-custom-element-registry.min.js.map"
+--assume_function_wrapper=true
+--rewrite_polyfills=false
+--create_source_map=./scoped-custom-element-registry.min.js.map
+--source_map_include_content

packages/scoped-custom-element-registry/gulpfile.js

@@ -47,9 +47,14 @@
   },
   "wireit": {
     "build": {
-      "command": "gulp",
+      "dependencies": [
+        "build:closure"
+      ]
+    },
+    "build:closure": {
+      "command": "google-closure-compiler --flagfile closure-flags.txt",
       "files": [
-        "gulpfile.js",
+        "closure-flags.txt",
         "src/**/*.js"
       ],
       "output": [