diff --git a/lib/mixins/template-stamp.js b/lib/mixins/template-stamp.js
index e7a576ec2a..736091416a 100644
--- a/lib/mixins/template-stamp.js
+++ b/lib/mixins/template-stamp.js
@@ -22,6 +22,49 @@ const templateExtensions = {
'dom-if': true,
'dom-repeat': true
};
+
+let placeholderBugDetect = false;
+let placeholderBug = false;
+
+function hasPlaceholderBug() {
+ if (!placeholderBugDetect) {
+ const t = document.createElement('textarea');
+ t.placeholder = 'a';
+ placeholderBug = t.placeholder === t.textContent;
+ }
+ return placeholderBug;
+}
+
+/**
+ * Some browsers have a bug with textarea, where placeholder text is copied as
+ * a textnode child of the textarea.
+ *
+ * If the placeholder is a binding, this can break template stamping in two
+ * ways.
+ *
+ * One issue is that when the `placeholder` binding is removed, the textnode
+ * child of the textarea is deleted, and the template info tries to bind into
+ * that node.
+ *
+ * When `legacyOptimizations` is enabled, the node is removed from the textarea
+ * when the `placeholder` binding is processed, leaving an "undefined" cell in
+ * the binding metadata object.
+ *
+ * When `legacyOptimizations` is disabled, the template is cloned before
+ * processing, and has an extra binding to the textContent of the text node
+ * child of the textarea. This at best is an extra binding to process that has
+ * no useful effect, and at worst throws exceptions trying to update the text
+ * node.
+ *
+ * @param {!Node} node Check node for placeholder bug
+ * @return {boolean} True if placeholder is bugged
+ */
+function shouldFixPlaceholder(node) {
+ return hasPlaceholderBug()
+ && node.localName === 'textarea' && node.placeholder
+ && node.placeholder === node.textContent;
+}
+
function wrapTemplateExtension(node) {
let is = node.getAttribute('is');
if (is && templateExtensions[is]) {
@@ -251,6 +294,9 @@ export const TemplateStamp = dedupingMixin(
// For ShadyDom optimization, indicating there is an insertion point
templateInfo.hasInsertionPoint = true;
}
+ if (shouldFixPlaceholder(node)) {
+ node.textContent = null;
+ }
if (element.firstChild) {
this._parseTemplateChildNodes(element, templateInfo, nodeInfo);
}
diff --git a/test/unit/property-effects-template.html b/test/unit/property-effects-template.html
index 2f761f672a..56327de127 100644
--- a/test/unit/property-effects-template.html
+++ b/test/unit/property-effects-template.html
@@ -13,7 +13,6 @@
-
@@ -282,9 +281,10 @@