diff --git a/lib/legacy/legacy-element-mixin.html b/lib/legacy/legacy-element-mixin.html
index 28c29cbe0a..7306c65140 100644
--- a/lib/legacy/legacy-element-mixin.html
+++ b/lib/legacy/legacy-element-mixin.html
@@ -164,6 +164,7 @@
        *
        * @return {void}
        * @override
+       * @suppress {invalidCasts}
        */
       _initializeProperties() {
         let proto = Object.getPrototypeOf(this);
@@ -172,7 +173,7 @@
           this._registered();
         }
         super._initializeProperties();
-        this.root = this;
+        this.root = /** @type {HTMLElement} */(this);
         this.created();
       }
 
diff --git a/package-lock.json b/package-lock.json
index a8d8014ef2..c6934a2378 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4192,9 +4192,9 @@
       }
     },
     "google-closure-compiler": {
-      "version": "20171112.0.0",
-      "resolved": "https://registry.npmjs.org/google-closure-compiler/-/google-closure-compiler-20171112.0.0.tgz",
-      "integrity": "sha1-eHENtO+J/1QGOdgA5tWffLfPLZg=",
+      "version": "20180204.0.0",
+      "resolved": "https://registry.npmjs.org/google-closure-compiler/-/google-closure-compiler-20180204.0.0.tgz",
+      "integrity": "sha1-sJf/t1DGXKB6LaRp12xVHTuOIaM=",
       "dev": true,
       "requires": {
         "chalk": "1.1.3",
diff --git a/package.json b/package.json
index 3d315d6da3..3ca1c4521f 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,7 @@
     "dom5": "^2.3.0",
     "eslint-plugin-html": "^4.0.1",
     "fs-extra": "^4.0.3",
-    "google-closure-compiler": "^20171112.0.0",
+    "google-closure-compiler": "^20180204.0.0",
     "gulp": "^3.9.1",
     "gulp-babel": "^6.1.2",
     "gulp-eslint": "^4.0.0",