project.xml: use -dce no compiler option for Flash swc

Author: joshtynjala

project.xml

@@ -15,6 +15,11 @@
 	<section if="flash">
 		<source path="build_macros/flash"/>
 		<haxeflag name="--macro" value="AddFlashPropertyMeta.find('feathers.validators')"/>
+		<!--
+			don't remove dead code because other libraries that depend on
+			this one, and need to build .swc files too, might need it
+		 -->
+		<haxeflag name="-dce" value="no"/>
 	</section>
 
 	<section if="find_missing_docs">