Simplify logic for disable-upgrade

Author: Steven Orvell

lib/legacy/class.js

@@ -238,6 +238,24 @@ function GenerateClassFromInfo(info, Base, behaviors) {
       return observedAttributesGetter.call(this).concat(DISABLED_ATTR);
     }
 
+    // Prevent element from initializing properties when it's upgrade disabled.
+    /** @override */
+    _initializeProperties() {
+      if (!this.hasAttribute(DISABLED_ATTR)) {
+        super._initializeProperties();
+      } else {
+        this.__isUpgradeDisabled = true;
+      }
+    }
+
+    // Prevent element from enabling properties when it's upgrade disabled.
+    /** @override */
+    _enableProperties() {
+      if (!this.__isUpgradeDisabled) {
+        super._enableProperties();
+      }
+    }
+
     /**
      * @override
      * @param {string} name Attribute name.
@@ -248,48 +266,33 @@ function GenerateClassFromInfo(info, Base, behaviors) {
      */
     attributeChangedCallback(name, old, value, namespace) {
       if (name == DISABLED_ATTR) {
-        if (!this.__dataEnabled && value == null && this.isConnected) {
-          super.connectedCallback();
+        // When disable-upgrade is removed, intialize properties and
+        // provoke connectedCallback if the element is already connected.
+        if (!this.__dataEnabled && value == null) {
+          super._initializeProperties();
+          this.__isUpgradeDisabled = false;
+          if (this.isConnected) {
+            super.connectedCallback();
+          }
         }
       } else {
         super.attributeChangedCallback(
             name, old, value, /** @type {null|string} */ (namespace));
       }
     }
 
-
-    // prevent user code in connected from running
+    // Prevent element from connecting when it's upgrade disabled.
     /** @override */
     connectedCallback() {
-      if (this.__dataEnabled || !this.hasAttribute(DISABLED_ATTR)) {
+      if (!this.__isUpgradeDisabled) {
         super.connectedCallback();
       }
     }
 
-    _initializeProperties() {
-      if (!this.hasAttribute(DISABLED_ATTR)) {
-        super._initializeProperties();
-      } else {
-        this.__wasDisabled = true;
-      }
-    }
-
-    // prevent element from turning on properties
-    /** @override */
-    _enableProperties() {
-      if (this.__wasDisabled) {
-        this.__wasDisabled = false;
-        super._initializeProperties();
-      }
-      if (!this.hasAttribute(DISABLED_ATTR)) {
-        super._enableProperties();
-      }
-    }
-
-    // only go if "enabled"
+    // Prevent element from disconnecting when it's upgrade disabled.
     /** @override */
     disconnectedCallback() {
-      if (this.__dataEnabled) {
+      if (!this.__isUpgradeDisabled) {
         super.disconnectedCallback();
       }
     }