DevTools: Fix 'Add new class' placeholder text

third_party/WebKit/Source/devtools/front_end/elements/ClassesPaneWidget.js

Index: third_party/WebKit/Source/devtools/front_end/elements/ClassesPaneWidget.js
diff --git a/third_party/WebKit/Source/devtools/front_end/elements/ClassesPaneWidget.js b/third_party/WebKit/Source/devtools/front_end/elements/ClassesPaneWidget.js
index c996daeec680c7a66390659003f5ab7a3a453964..d02f4b5b6d70f7ec7e33542b71fb9be4d64aef08 100644
--- a/third_party/WebKit/Source/devtools/front_end/elements/ClassesPaneWidget.js
+++ b/third_party/WebKit/Source/devtools/front_end/elements/ClassesPaneWidget.js
@@ -10,7 +10,6 @@ Elements.ClassesPaneWidget = class extends UI.Widget {
     this.element.className = 'styles-element-classes-pane';
     var container = this.element.createChild('div', 'title-container');
     this._input = container.createChild('div', 'new-class-input monospace');
-    this._input.setAttribute('placeholder', Common.UIString('Add new class'));
     this.setDefaultFocusedElement(this._input);
     this._classesContainer = this.element.createChild('div', 'source-code');
     this._classesContainer.classList.add('styles-element-classes-container');
@@ -19,6 +18,7 @@ Elements.ClassesPaneWidget = class extends UI.Widget {
     this._prompt.renderAsBlock();
 
     var proxyElement = this._prompt.attach(this._input);
+    this._prompt.setPlaceholder(Common.UIString('Add new class'));
     proxyElement.addEventListener('keydown', this._onKeyDown.bind(this), false);
 
     SDK.targetManager.addModelListener(SDK.DOMModel, SDK.DOMModel.Events.DOMMutated, this._onDOMMutated, this);