DevTools: roll CodeMirror to v4.0.3

Source/devtools/front_end/cm/headlesscodemirror.js

Index: Source/devtools/front_end/cm/headlesscodemirror.js
diff --git a/Source/devtools/front_end/cm/headlesscodemirror.js b/Source/devtools/front_end/cm/headlesscodemirror.js
index 3433e8d17fcef6109f3f50997921c928e9ebdee6..67c7866b76a720e2be0cb16e66aa0d3e9a2f47c6 100644
--- a/Source/devtools/front_end/cm/headlesscodemirror.js
+++ b/Source/devtools/front_end/cm/headlesscodemirror.js
@@ -1,8 +1,6 @@
 // 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() {
@@ -152,4 +150,5 @@ CodeMirror.runMode = function (string, modespec, callback, options) {
   }
 };
 })();
+
 }(this))