DevTools: [CodeMirror] add Cmd-Backspace for the mac text editor

Source/devtools/front_end/source_frame/CodeMirrorTextEditor.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:
  *
  *     * 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 95 matching lines @@
         "Cmd-Up": "goDocStart",
         "Cmd-Down": "goDocEnd",
         "Alt-Left": "goGroupLeft",
         "Alt-Right": "goGroupRight",
         "Ctrl-Left": "moveCamelLeft",
         "Ctrl-Right": "moveCamelRight",
         "Shift-Ctrl-Left": "selectCamelLeft",
         "Shift-Ctrl-Right": "selectCamelRight",
         "Cmd-Left": "goLineStartSmart",
         "Cmd-Right": "goLineEnd",
+        "Cmd-Backspace": "delLineLeft",
         "Alt-Backspace": "delGroupBefore",
         "Alt-Delete": "delGroupAfter",
         "Cmd-/": "toggleComment",
         "Cmd-D": "selectNextOccurrence",
         "Cmd-U": "undoLastSelection",
         fallthrough: "devtools-common"
     };
 
     WebInspector.settings.textEditorIndent.addChangeListener(this._onUpdateEditorIndentation, this);
     WebInspector.settings.textEditorAutoDetectIndent.addChangeListener(this._onUpdateEditorIndentation, this);
@@ skipping 2019 matching lines @@
 WebInspector.CodeMirrorTextEditor._overrideModeWithPrefixedTokens("javascript", "js-");
 WebInspector.CodeMirrorTextEditor._overrideModeWithPrefixedTokens("xml", "xml-");
 
 /** @typedef {{lineNumber: number, event: !Event}} */
 WebInspector.CodeMirrorTextEditor.GutterClickEventData;
 
 /** @enum {string} */
 WebInspector.CodeMirrorTextEditor.Events = {
     GutterClick: "GutterClick"
 }