minor consolidations (#2484)

- unique symbol generation
- `unsafe` on `AST_Call`

lib/compress.js

@@ -2778,18 +2778,29 @@ merge(Compressor.prototype, {
         return self;
     });
 
+    AST_Scope.DEFMETHOD("make_var_name", function(prefix) {
+        var var_names = this.var_names;
+        if (!var_names) {
+            this.var_names = var_names = Object.create(null);
+            this.enclosed.forEach(function(def) {
+                var_names[def.name] = true;
+            });
+            this.variables.each(function(def, name) {
+                var_names[name] = true;
+            });
+        }
+        prefix = prefix.replace(/[^a-z_$]+/ig, "_");
+        var name = prefix;
+        for (var i = 0; var_names[name]; i++) name = prefix + "$" + i;
+        var_names[name] = true;
+        return name;
+    });
+
     AST_Scope.DEFMETHOD("hoist_properties", function(compressor){
         var self = this;
         if (!compressor.option("hoist_props") || compressor.has_directive("use asm")) return self;
         var top_retain = self instanceof AST_Toplevel && compressor.top_retain || return_false;
         var defs_by_id = Object.create(null);
-        var var_names = Object.create(null);
-        self.enclosed.forEach(function(def) {
-            var_names[def.name] = true;
-        });
-        self.variables.each(function(def, name) {
-            var_names[name] = true;
-        });
         return self.transform(new TreeTransformer(function(node) {
             if (node instanceof AST_VarDef) {
                 var sym = node.name, def, value;
@@ -2829,17 +2840,13 @@ merge(Compressor.prototype, {
             }
 
             function make_sym(key) {
-                var prefix = sym.name + "_" + key.toString().replace(/[^a-z_$]+/ig, "_");
-                var name = prefix;
-                for (var i = 0; var_names[name]; i++) name = prefix + "$" + i;
                 var new_var = make_node(sym.CTOR, sym, {
-                    name: name,
+                    name: self.make_var_name(sym.name + "_" + key),
                     scope: self
                 });
                 var def = self.def_variable(new_var);
                 defs.set(key, def);
                 self.enclosed.push(def);
-                var_names[name] = true;
                 return new_var;
             }
         }));
@@ -3408,8 +3415,7 @@ merge(Compressor.prototype, {
             self.args.length = last;
         }
         if (compressor.option("unsafe")) {
-            if (is_undeclared_ref(exp)) {
+            if (is_undeclared_ref(exp)) switch (exp.name) {
-                switch (exp.name) {
               case "Array":
                 if (self.args.length != 1) {
                     return make_node(AST_Array, self, {
@@ -3452,16 +3458,16 @@ merge(Compressor.prototype, {
                     operator: "!"
                 }).optimize(compressor);
                 break;
-                }
+            } else if (exp instanceof AST_Dot) switch(exp.property) {
-            }
+              case "toString":
-            else if (exp instanceof AST_Dot && exp.property == "toString" && self.args.length == 0) {
+                if (self.args.length == 0) return make_node(AST_Binary, self, {
-                return make_node(AST_Binary, self, {
                     left: make_node(AST_String, self, { value: "" }),
                     operator: "+",
                     right: exp.expression
                 }).optimize(compressor);
-            }
+                break;
-            else if (exp instanceof AST_Dot && exp.expression instanceof AST_Array && exp.property == "join") EXIT: {
+              case "join":
+                if (exp.expression instanceof AST_Array) EXIT: {
                     var separator;
                     if (self.args.length > 0) {
                         separator = self.args[0].evaluate(compressor);
@@ -3523,7 +3529,9 @@ merge(Compressor.prototype, {
                     node.expression.expression.elements = elements;
                     return best_of(compressor, self, node);
                 }
-            else if (exp instanceof AST_Dot && exp.expression.is_string(compressor) && exp.property == "charAt") {
+                break;
+              case "charAt":
+                if (exp.expression.is_string(compressor)) {
                     var arg = self.args[0];
                     var index = arg ? arg.evaluate(compressor) : 0;
                     if (index !== arg) {
@@ -3533,6 +3541,8 @@ merge(Compressor.prototype, {
                         }).optimize(compressor);
                     }
                 }
+                break;
+            }
         }
         if (compressor.option("unsafe_Func")
             && is_undeclared_ref(exp)