[DevTools] Cleanup DOMExtension.js.

third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js

Index: third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js b/third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js
index 0532a9d755c0e16ddb3dbd5394821c13bbe770b6..7753aa4381df30a8c51d909b7026607eda802b70 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/TextPrompt.js
@@ -687,7 +687,12 @@ WebInspector.TextPrompt.prototype = {
      */
     isCaretInsidePrompt: function()
     {
-        return this._element.isInsertionCaretInside();
+        var selection = this._element.getComponentSelection();
+        // @see crbug.com/602541
+        var selectionRange = selection && selection.rangeCount ? selection.getRangeAt(0) : null;
+        if (!selectionRange || !selection.isCollapsed)
+            return false;
+        return selectionRange.startContainer.isSelfOrDescendant(this._element);
     },
 
     /**