DevTools: Migrate from -webkit-user-modify to contenteditable

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

Index: third_party/WebKit/Source/devtools/front_end/ui/InplaceEditor.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/InplaceEditor.js b/third_party/WebKit/Source/devtools/front_end/ui/InplaceEditor.js
index 963a687e11bef5993c5901085b5dbb909b074b1f..794ef4c6639b9e0574da4237cd6eff1b6a49840b 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/InplaceEditor.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/InplaceEditor.js
@@ -30,6 +30,7 @@ UI.InplaceEditor = class {
   setUpEditor(editingContext) {
     var element = editingContext.element;
     element.classList.add('editing');
+    element.setAttribute('contenteditable', 'plaintext-only');
 
     var oldTabIndex = element.getAttribute('tabIndex');
     if (typeof oldTabIndex !== 'number' || oldTabIndex < 0)
@@ -41,6 +42,7 @@ UI.InplaceEditor = class {
   closeEditor(editingContext) {
     var element = editingContext.element;
     element.classList.remove('editing');
+    element.removeAttribute('contenteditable');
 
     if (typeof editingContext.oldTabIndex !== 'number')
       element.removeAttribute('tabIndex');