[DevTools] Prepare to move Popover to shadow DOM.

third_party/WebKit/Source/devtools/front_end/source_frame/UISourceCodeFrame.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  * 1. Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *
@@ skipping 476 matching lines @@
 SourceFrame.UISourceCodeFrame.RowMessage = class {
   /**
    * @param {!Workspace.UISourceCode.Message} message
    */
   constructor(message) {
     this._message = message;
     this._repeatCount = 1;
     this.element = createElementWithClass('div', 'text-editor-row-message');
     this._icon = this.element.createChild('label', '', 'dt-icon-label');
     this._icon.type = SourceFrame.UISourceCodeFrame._iconClassPerLevel[message.level()];
-    this._repeatCountElement = this.element.createChild('label', 'message-repeat-count hidden', 'dt-small-bubble');
+    this._repeatCountElement =
+        this.element.createChild('label', 'text-editor-row-message-repeat-count hidden', 'dt-small-bubble');
     this._repeatCountElement.type = SourceFrame.UISourceCodeFrame._bubbleTypePerLevel[message.level()];
-    var linesContainer = this.element.createChild('div', 'text-editor-row-message-lines');
+    var linesContainer = this.element.createChild('div');
     var lines = this._message.text().split('\n');
     for (var i = 0; i < lines.length; ++i) {
       var messageLine = linesContainer.createChild('div');
       messageLine.textContent = lines[i];
     }
   }
 
   /**
    * @return {!Workspace.UISourceCode.Message}
    */
@@ skipping 62 matching lines @@
       this.textEditor.removeDecoration(this._decoration, lineNumber);
     this._hasDecoration = true;
     this.textEditor.addDecoration(this._decoration, lineNumber, Math.max(columnNumber - 1, lineIndent));
   }
 
   /**
    * @return {!Element}
    */
   messagesDescription() {
     this._messagesDescriptionElement.removeChildren();
+    UI.appendStyle(this._messagesDescriptionElement, 'source_frame/messagesPopover.css');
     for (var i = 0; i < this._messages.length; ++i)
       this._messagesDescriptionElement.appendChild(this._messages[i].element);
 
     return this._messagesDescriptionElement;
   }
 
   detachFromEditor() {
     var position = this._lineHandle.resolve();
     if (!position)
       return;
@@ skipping 84 matching lines @@
 
 /**
  * @param {!Workspace.UISourceCode.Message} a
  * @param {!Workspace.UISourceCode.Message} b
  * @return {number}
  */
 Workspace.UISourceCode.Message.messageLevelComparator = function(a, b) {
   return Workspace.UISourceCode.Message._messageLevelPriority[a.level()] -
       Workspace.UISourceCode.Message._messageLevelPriority[b.level()];
 };