fix linting errors

.eslintrc.json

@@ -18,6 +18,7 @@
     "Polymer": true,
     "ShadyDOM": true,
     "ShadyCSS": true,
-    "ApplyShim": true
+    "ApplyShim": true,
+    "goog": true
   }
 }

src/elements/legacy-element.html

@@ -89,7 +89,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
 
       detached() {}
 
-      attributeChanged(name, old, value) {}
+      attributeChanged(name, old, value) {} // eslint-disable-line no-unused-vars
 
       serialize(value) {
         return this._serializeAttribute(value);

src/properties/property-effects.html

@@ -1817,9 +1817,9 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         } else {
           if (!this._hasReadOnlyEffect(/** @type {string} */(path))) {
             /** @type {?string | undefined} */
-            let propPath;
-            if ((propPath = this._setPathOrUnmanagedProperty(path, value))) {
-              this._setProperty(path, value);
+            let propPath = this._setPathOrUnmanagedProperty(path, value);
+            if (propPath) {
+              this._setProperty(propPath, value);
             }
           }
         }

src/utils/boot.html

@@ -12,6 +12,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
   window.Polymer = window.Polymer || {};
   window.Polymer.version = '2.0-preview';
 
+  /* eslint-disable no-unused-vars */
   var goog = {
     reflect: {
       objectProperty(s, o) {
@@ -19,5 +20,5 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
       }
     }
   }
-
+  /* eslint-enable */
 </script>