dev: fix gulp-watch cpu usage

gulpfile.js

@@ -46,7 +46,10 @@ const common = {
   },
 
   keepSyncResourceFile () {
-    return gulp.watch(resourceFilePath, { ignoreInitial: true }, common.syncResourceFile)
+    return gulp.watch(resourceFilePath, { 
+      ignoreInitial: true,
+      usePolling: false  // Don't know why but have to set explicitly, or high cpu usage
+     }, common.syncResourceFile)
   },
 
   syncAllStatic () {
@@ -67,7 +70,10 @@ const common = {
     return gulp.watch([
       path.join(outputPath, 'js/**'),
       path.join(outputPath, 'css/**')
-    ], { ignoreInitial: true }, common.syncJS_CSSinRt)
+    ], { 
+      ignoreInitial: true,
+      usePolling: false  // Don't know why but have to set explicitly, or high cpu usage
+    }, common.syncJS_CSSinRt)
   }
 }