fix: className conflict to keyword like constuctor or toString (#1)

src/index.js

@@ -58,7 +58,7 @@ const processor = postcss.plugin('postcss-modules-scope', function(options) {
     const generateScopedName =
       (options && options.generateScopedName) || processor.generateScopedName;
 
-    const exports = {};
+    const exports = Object.create(null);
 
     function exportScopedName(name) {
       const scopedName = generateScopedName(

test/test-cases/export-keywords-selector/expected.css

@@ -0,0 +1,12 @@
+._input__constructor {
+  color: green;
+}
+
+._input__toString {
+  color: red;
+}
+
+:export {
+  constructor: _input__constructor;
+  toString: _input__toString;
+}

test/test-cases/export-keywords-selector/source.css

@@ -0,0 +1,7 @@
+:local(.constructor) {
+  color: green;
+}
+
+:local(.toString) {
+  color: red;
+}