[DevTools] Allow arrow keys to increment/decrement value in numeric inputs.

Source/devtools/front_end/ui/SettingsUI.js

 /*
  * Copyright (C) 2014 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 114 matching lines @@
         if (validatorCallback)
             validate();
         if (instant)
             apply();
     }
 
     function onKeyDown(event)
     {
         if (isEnterKey(event))
             apply();
+        incrementForArrows(event);
+    }
+
+    function incrementForArrows(event)
+    {
+        if (!numeric)
+            return;
+
+        var increment = event.keyIdentifier === "Up" ? 1 : event.keyIdentifier === "Down" ? -1 : 0;
+        if (!increment)
+            return;
+        if (event.shiftKey)
+            increment *= 10;
+
+        var value = inputElement.value;
+        if (validatorCallback && validatorCallback(value))

[vsevik, 2014/07/02 15:17:25]

Looks like this is not really needed.

[dgozman, 2014/07/02 15:50:17]

This is to do nothing if user enters "abc" and presses up key. Otherwise we
change to "1".

+            return;
+        value = Number(value);
+        if (clearForZero && !value)

[vsevik, 2014/07/02 15:17:25]

So we'll never increment zero?

[dgozman, 2014/07/02 15:50:17]

Yes, if we replace zero value by empty string (used in responsive design view).

+            return;
+        value += increment;
+        if (clearForZero && !value)

[vsevik, 2014/07/02 15:17:25]

Why?

[dgozman, 2014/07/02 15:50:17]

Same reasons. I don't want to switch from "1" to empty string by pressing arrow
key.

+            return;
+        value = String(value);
+        if (validatorCallback && validatorCallback(value))
+            return;
+
+        inputElement.value = value;
+        apply();
+        event.preventDefault();
     }
 
     function validate()
     {
         var error = validatorCallback(inputElement.value);
         if (!error)
             error = "";
         inputElement.classList.toggle("error-input", !!error);
         errorMessageLabel.textContent = error;
     }
@@ skipping 113 matching lines @@
 
 WebInspector.UISettingDelegate.prototype = {
     /**
      * @return {?Element}
      */
     settingElement: function()
     {
         return null;
     }
 }