Removed dependency to async API

Author: salmonb

webfx-demo-particles-application-gwt/src/main/module.gwt.xml

@@ -172,7 +172,6 @@
     <!-- used by webfx-platform-shared-scheduler (SOURCE) -->
     <!-- used by webfx-platform-shared-shutdown (SOURCE) -->
     <source path="dev/webfx/platform/shared/util"/>
-    <source path="dev/webfx/platform/shared/util/async"/>
     <source path="dev/webfx/platform/shared/util/collection"/>
     <source path="dev/webfx/platform/shared/util/function"/>
     <source path="dev/webfx/platform/shared/util/noreflect"/>