Allow empty destructuring (#1773)

lib/ast.js

@@ -448,8 +448,6 @@ var AST_ArrowParametersOrSeq = DEFNODE("ArrowParametersOrSeq", "expressions", {
             } else if (ex instanceof AST_Hole) {
                 return ex;
             } else if (ex instanceof AST_Destructuring) {
-                if (ex.names.length == 0)
-                    croak("Invalid destructuring function parameter", ex.start.line, ex.start.col);
                 ex.names = ex.names.map(to_fun_args);
                 return insert_default(ex, default_seen_above);
             } else if (ex instanceof AST_SymbolRef) {

test/compress/harmony.js

@@ -314,11 +314,13 @@ default_assign: {
         function f(a, b = 3) {
             console.log(a);
         }
+        g = ([[] = 123]) => {};
     }
     expect: {
         function f(a) {
             console.log(a);
         }
+        g = ([[] = 123]) => {};
     }
 }