DevTools: do not allow using 'this' before call into super.

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

 /*
  * Copyright (C) 2011 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 31 matching lines @@
     WebInspector.SimpleView.call(this, WebInspector.UIString("Source"));
 
     this._url = url;
     this._lazyContent = lazyContent;
 
     this._textEditor = new WebInspector.SourcesTextEditor(this);
 
     this._currentSearchResultIndex = -1;
     this._searchResults = [];
 
-    this._textEditor.setReadOnly(!this.canEditSource());
     this._textEditor.addEventListener(WebInspector.SourcesTextEditor.Events.EditorFocused, this._resetCurrentSearchResultIndex, this);
     this._textEditor.addEventListener(WebInspector.SourcesTextEditor.Events.SelectionChanged, this._updateSourcePosition, this);
     this._textEditor.addEventListener(WebInspector.SourcesTextEditor.Events.TextChanged, event => this.onTextChanged(event.data.oldRange, event.data.newRange));
 
     this._shortcuts = {};
     this.element.addEventListener("keydown", this._handleKeyDown.bind(this), false);
 
     this._sourcePosition = new WebInspector.ToolbarText();
 
     /**
      * @type {?WebInspector.SearchableView}
      */
     this._searchableView = null;
+    this._editable = false;
 };
 
 WebInspector.SourceFrame.prototype = {
     /**
+     * @param {boolean} editable
+     */
+    setEditable: function(editable)
+    {
+        this._editable = editable;
+        this._textEditor.setReadOnly(editable);
+    },
+
+    /**
      * @param {number} key
      * @param {function():boolean} handler
      */
     addShortcut: function(key, handler)
     {
         this._shortcuts[key] = handler;
     },
 
     /**
      * @override
@@ skipping 481 matching lines @@
     populateTextAreaContextMenu: function(contextMenu, lineNumber, columnNumber)
     {
         return Promise.resolve();
     },
 
     /**
      * @return {boolean}
      */
     canEditSource: function()
     {
-        return false;
+        return this._editable;
     },
 
     _updateSourcePosition: function()
     {
         var selections = this._textEditor.selections();
         if (!selections.length)
             return;
         if (selections.length > 1) {
             this._sourcePosition.setText(WebInspector.UIString("%d selection regions", selections.length));
             return;
@@ skipping 15 matching lines @@
     _handleKeyDown: function(e)
     {
         var shortcutKey = WebInspector.KeyboardShortcut.makeKeyFromEvent(e);
         var handler = this._shortcuts[shortcutKey];
         if (handler && handler())
             e.consume(true);
     },
 
     __proto__: WebInspector.SimpleView.prototype
 };