DevTools: Remove unused variables. Disallow unused variables with eslint

third_party/WebKit/Source/devtools/front_end/sdk/DebuggerModel.js

 /*
  * Copyright (C) 2010 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 198 matching lines @@
     // Adjust column if needed.
     var minColumnNumber = 0;
     var scripts = this._scriptsBySourceURL.get(url) || [];
     for (var i = 0, l = scripts.length; i < l; ++i) {
       var script = scripts[i];
       if (lineNumber === script.lineOffset)
         minColumnNumber = minColumnNumber ? Math.min(minColumnNumber, script.columnOffset) : script.columnOffset;
     }
     columnNumber = Math.max(columnNumber, minColumnNumber);
 
-    var target = this.target();
     /**
      * @param {?Protocol.Error} error
      * @param {!Protocol.Debugger.BreakpointId} breakpointId
      * @param {!Array.<!Protocol.Debugger.Location>} locations
      * @this {SDK.DebuggerModel}
      */
     function didSetBreakpoint(error, breakpointId, locations) {
       if (callback) {
         var rawLocations = locations ?
             locations.map(SDK.DebuggerModel.Location.fromPayload.bind(SDK.DebuggerModel.Location, this)) :
             [];
         callback(error ? null : breakpointId, rawLocations);
       }
     }
     this._agent.setBreakpointByUrl(lineNumber, url, undefined, columnNumber, condition, didSetBreakpoint.bind(this));
   }
 
   /**
    * @param {!SDK.DebuggerModel.Location} rawLocation
    * @param {string} condition
    * @param {function(?Protocol.Debugger.BreakpointId, !Array.<!SDK.DebuggerModel.Location>)=} callback
    */
   setBreakpointBySourceId(rawLocation, condition, callback) {
-    var target = this.target();
-
     /**
      * @this {SDK.DebuggerModel}
      * @param {?Protocol.Error} error
      * @param {!Protocol.Debugger.BreakpointId} breakpointId
      * @param {!Protocol.Debugger.Location} actualLocation
      */
     function didSetBreakpoint(error, breakpointId, actualLocation) {
       if (callback) {
         if (error || !actualLocation) {
           callback(null, []);
@@ skipping 1058 matching lines @@
         stack.callFrames.shift();
       if (previous && !stack.callFrames.length)
         previous.parent = stack.parent;
       else
         previous = stack;
       stack = stack.parent;
     }
     return asyncStackTrace;
   }
 };