Merge pull request #920 from sveltejs/gh-919

add tslib and use importHelpers - fixes #919

package.json

@@ -81,5 +81,8 @@
       "src/**/__test__.js",
       "src/shared/**"
     ]
+  },
+  "dependencies": {
+    "tslib": "^1.8.0"
   }
 }

tsconfig.json

@@ -5,7 +5,8 @@
         "noImplicitThis": true,
         "noEmitOnError": true,
         "allowJs": true,
-        "lib": ["es5", "es6", "dom"]
+        "lib": ["es5", "es6", "dom"],
+        "importHelpers": true
     },
     "target": "ES5",
     "include": [