From 83834aff18eb13d9e67a487542515daf11de65e1 Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Tue, 28 Aug 2018 14:48:13 -0400
Subject: [PATCH 1/3] Upstream changes to externs

---
 externs/polymer-externs.js       | 17 ++++++++++++++++-
 externs/webcomponents-externs.js | 16 ++++++++--------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/externs/polymer-externs.js b/externs/polymer-externs.js
index 7c0ede16aa..45d21181d0 100644
--- a/externs/polymer-externs.js
+++ b/externs/polymer-externs.js
@@ -78,6 +78,21 @@ function Polymer(init){}
  */
 Polymer.sanitizeDOMValue;
 
+/**
+ * @type {boolean}
+ */
+Polymer.passiveTouchGestures;
+
+/**
+ * @type {boolean}
+ */
+Polymer.strictTemplatePolicy;
+
+/**
+ * @type {boolean}
+ */
+Polymer.allowTemplateFromDomModule;
+
 /**
  * @param {string} string
  * @param {Object} obj
@@ -172,7 +187,7 @@ var PolymerDeepPropertyChange;
  * @constructor
  * @template T
  */
-let DomRepeatEvent = function() {};
+var DomRepeatEvent = function() {};
 
 /**
  * @type {{
diff --git a/externs/webcomponents-externs.js b/externs/webcomponents-externs.js
index 8bcf4cede5..029cf4fea4 100644
--- a/externs/webcomponents-externs.js
+++ b/externs/webcomponents-externs.js
@@ -12,37 +12,37 @@
  */
 /* eslint-disable */
 
-let HTMLImports = {
+var HTMLImports = {
   /**
    * @param {function()} callback
    */
-  whenReady(callback){},
+  whenReady(callback) {},
   /**
    * @param {Element} element
    * @returns {Document} document
    */
-  importForElement(element){}
+  importForElement(element) {}
 };
 
 window.HTMLImports = HTMLImports;
 
-let ShadyDOM = {
+var ShadyDOM = {
   inUse: false,
-  flush(){},
+  flush() {},
   /**
    * @param {!Node} target
    * @param {function(Array<MutationRecord>, MutationObserver)} callback
    * @return {MutationObserver}
    */
-  observeChildren(target, callback){},
+  observeChildren(target, callback) {},
   /**
    * @param {MutationObserver} observer
    */
-  unobserveChildren(observer){},
+  unobserveChildren(observer) {},
   /**
    * @param {Node} node
    */
-  patch(node){}
+  patch(node) {}
 };
 
 window.ShadyDOM = ShadyDOM;

From b4d6e70a1168d81781a455d19b748cfd73d22246 Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Tue, 28 Aug 2018 17:53:27 -0400
Subject: [PATCH 2/3] Upstream warning text.

---
 lib/legacy/legacy-data-mixin.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/legacy/legacy-data-mixin.js b/lib/legacy/legacy-data-mixin.js
index 5aee1e0209..2d18397d6a 100644
--- a/lib/legacy/legacy-data-mixin.js
+++ b/lib/legacy/legacy-data-mixin.js
@@ -40,7 +40,7 @@ function wrapEffect(effect, fnName) {
         fn.apply(this, arguments);
       } catch (e) {
         if (e instanceof UndefinedArgumentError) {
-          console.warn(`Argument '${e.arg}'${fnName ?` for method '${fnName}'` : ''} was undefined. Ensure it has an undefined check.`);
+          console.warn(`Argument '${e.arg}'${fnName ?` for method '${fnName}'` : ''} was undefined. Ensure it has a default value, or else ensure the method handles the argument being undefined.`);
         } else {
           throw e;
         }
@@ -98,7 +98,7 @@ export const LegacyDataMixin = dedupingMixin(superClass => {
             // Break out of effect's control flow; will be caught in
             // wrapped property effect function below
             const name = args[i].name;
-            throw new UndefinedArgumentError(`Argument '${name}' is undefined. Ensure it has an undefined check.`, name);
+            throw new UndefinedArgumentError(`Argument '${name}' is undefined.`, name);
           }
         }
       }

From e69c8b3c6e2bc58800f35a83089da806a6d8aa7c Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Tue, 28 Aug 2018 20:23:59 -0400
Subject: [PATCH 3/3] Fix jsdoc comment

---
 lib/legacy/legacy-data-mixin.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/legacy/legacy-data-mixin.js b/lib/legacy/legacy-data-mixin.js
index 2d18397d6a..3c61115f25 100644
--- a/lib/legacy/legacy-data-mixin.js
+++ b/lib/legacy/legacy-data-mixin.js
@@ -75,7 +75,8 @@ export const LegacyDataMixin = dedupingMixin(superClass => {
    * @constructor
    * @extends {superClass}
    * @unrestricted
-   * @private   */
+   * @private
+   */
   class LegacyDataMixin extends superClass {
     /**
      * Overrides `Polymer.PropertyEffects` to add `undefined` argument