DevTools: roll CodeMirror to v4.0.3

Source/devtools/front_end/cm/headlesscodemirror.js

 // Content of the function is equal to runmode-standalone.js file
 // from CodeMirror distribution
 (function(window) {
-/* Just enough of CodeMirror to run runMode under node.js */
-
 window.CodeMirror = {};
 
 (function() {
 "use strict";
 
 function splitLines(string){ return string.split(/\r?\n|\r/); };
 
 function StringStream(string) {
   this.pos = this.start = 0;
   this.string = string;
@@ skipping 129 matching lines @@
     if (i) callback("\n");
     var stream = new CodeMirror.StringStream(lines[i]);
     while (!stream.eol()) {
       var style = mode.token(stream, state);
       callback(stream.current(), style, i, stream.start, state);
       stream.start = stream.pos;
     }
   }
 };
 })();
+
 }(this))