fix "java.lang.UnsupportedOperationException" exception

- don't mutate parameters
- fails with r.script(Collections.EMPTY_MAP, body) call from
  https://github.com/grails/grails-core/blob/0479f60/grails-plugin-gsp/src/main/groovy/org/codehaus/groovy/grails/plugins/web/taglib/JavascriptTagLib.groovy#L135

grails-app/taglib/org/grails/plugin/resource/ResourceTagLib.groovy

@@ -390,25 +390,31 @@ class ResourceTagLib {
         DispositionsUtils.doneDispositionResources(request, dispositionToRender)
     }
 
-    def script = { attributes, body ->
+    def script = { attributesAsParam, body ->
+        def attributes = [:] + attributesAsParam
         attributes.type = "script"
         if (!attributes.disposition) {
             attributes.disposition = DispositionsUtils.DISPOSITION_DEFER
         }
 
-        stash(attributes, body)
+        doStash(attributes, body)
     }
 
-    def style = { attributes, body ->
+    def style = { attributesAsParam, body ->
+        def attributes = [:] + attributesAsParam
         attributes.type = "style"
         if (!attributes.disposition) {
             attributes.disposition = DispositionsUtils.DISPOSITION_HEAD
         }
 
-        stash(attributes, body)
+        doStash(attributes, body)
     }
-
+    
     def stash = { attributes, body ->
+        doStash(attributes, body)
+    }
+
+    private def doStash(attributes, body) {
         needsResourceLayout()
         StashManager.stashPageFragment(request, (String) attributes.type, (String) attributes.disposition, (String) body())
     }