minor clean-ups (#2686)

lib/output.js

@@ -671,9 +671,7 @@ function OutputStream(options) {
         }
     };
 
-    PARENS(AST_Node, function(){
-        return false;
-    });
+    PARENS(AST_Node, return_false);
 
     // a function expression needs parens around it when it's provably
     // the first token to appear in a statement.
@@ -699,9 +697,7 @@ function OutputStream(options) {
 
     // same goes for an object literal, because otherwise it would be
     // interpreted as a block of code.
-    PARENS(AST_Object, function(output){
-        return first_in_statement(output);
-    });
+    PARENS(AST_Object, first_in_statement);
 
     PARENS(AST_Unary, function(output){
         var p = output.parent();