Remove stringset dependency

package-lock.json

@@ -64,11 +64,6 @@
       "resolved": "https://registry.npmjs.org/stringmap/-/stringmap-0.2.2.tgz",
       "integrity": "sha1-VWwTeyWPlCuHdvWy71gqoGnX0bE="
     },
-    "stringset": {
-      "version": "0.2.1",
-      "resolved": "https://registry.npmjs.org/stringset/-/stringset-0.2.1.tgz",
-      "integrity": "sha1-7yWcTjSTRDd/zRyRPdLoSMnAQrU="
-    },
     "wordwrap": {
       "version": "0.0.3",
       "resolved": "https://registry.npmjs.org/wordwrap/-/wordwrap-0.0.3.tgz",

package.json

@@ -13,8 +13,7 @@
     "convert-source-map": "^1.1.2",
     "optimist": "^0.6.1",
     "source-map": "^0.5.3",
-    "stringmap": "^0.2.2",
-    "stringset": "^0.2.1"
+    "stringmap": "^0.2.2"
   },
   "devDependencies": {
     "coffee-script": "^1.10.0",

src/scope.js

@@ -6,7 +6,6 @@
 
 const assert = require("assert");
 const stringmap = require("stringmap");
-const stringset = require("stringset");
 
 module.exports = class Scope {
     constructor(args) {
@@ -45,7 +44,7 @@ module.exports = class Scope {
         // referenced in this scope (immediately or in child).
         // only stored on hoist scopes for efficiency
         // (because we currently generate lots of empty block scopes)
-        this.propagates = (this.kind === "hoist" ? stringset() : null);
+        this.propagates = (this.kind === "hoist" ? new Set() : null);
 
         // scopes register themselves with their parents for easier traversal
         if (this.parent) {