Fix host property syncing

lib/elements/dom-if.js

@@ -210,7 +210,6 @@ class DomIfBase extends PolymerElement {
         // No template found yet
         return;
       }
-      this.__syncHostProperties();
     } else if (this.restamp) {
       this.__teardownInstance();
     }
@@ -255,6 +254,12 @@ class DomIfFast extends DomIfBase {
     // (and any nested template effects) when the `if` is false
     templateInfo.runEffects = (runEffects, changedProps) => {
       if (this.if) {
+        const invalidProps = this.__invalidProps;
+        if (invalidProps) {
+          this.__squelchedRunEffects = this.__invalidProps = null;
+          this._showHideChildren();
+          changedProps = Object.assign(invalidProps, changedProps);
+        }
         runEffects(changedProps);
       } else {
         this.__invalidProps = Object.assign(this.__invalidProps || {}, changedProps);
@@ -267,10 +272,10 @@ class DomIfFast extends DomIfBase {
   }
 
   __syncHostProperties() {
-    const runEffects = this.__squelchedRunEffects;
-    if (runEffects) {
-      runEffects(this.__invalidProps);
-      this.__syncProps = this.__squelchedRunEffects = null;
+    const props = this.__invalidProps;
+    if (props) {
+      this.__squelchedRunEffects(this.__invalidProps);
+      this.__invalidProps = this.__squelchedRunEffects = null;
     }
   }
 
@@ -295,6 +300,9 @@ class DomIfFast extends DomIfBase {
     if (this.__instance) {
       showHideChildren(hidden, this.__instance.templateInfo.childNodes);
     }
+    if (!hidden) {
+      this.__syncHostProperties();
+    }
   }
 }
 
@@ -391,6 +399,9 @@ class DomIfLegacy extends DomIfBase {
     const hidden = this.__hideTemplateChildren__ || !this.if;
     if (this.__instance) {
       this.__instance._showHideChildren(hidden);
+      if (!hidden) {
+        this.__syncHostProperties();
+      }
     }
   }
 }

lib/utils/templatize.js

@@ -641,8 +641,10 @@ function warnOnUndeclaredProperties(templateInfo, options, methodHost) {
  *     model.set('item.checked', true);
  *   }
  *
- * @param {HTMLTemplateElement} template The model will be returned for
- *   elements stamped from this template
+ * @param {HTMLElement} template The model will be returned for
+ *   elements stamped from this template (accepts either an HTMLTemplateElement)
+ *   or a `<dom-if>`/`<dom-repeat>` element when using `removeNestedTemplates`
+ *   optimization.
  * @param {Node=} node Node for which to return a template model.
  * @return {TemplateInstanceBase} Template instance representing the
  *   binding scope for the element