One newline is enough.

git-svn-id: https://develop.svn.wordpress.org/trunk@19684 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/css/editor-buttons.dev.css

@@ -189,7 +189,6 @@
 	margin: 0 0 0 1px;
 }
 
-
 .wp_themeSkin a.mceButton:active,
 .wp_themeSkin a.mceButtonActive,
 .wp_themeSkin a.mceButtonActive:hover,
@@ -556,7 +555,6 @@
 	background: url("../js/tinymce/themes/advanced/skins/default/img/menu_arrow.gif") no-repeat top right;
 }
 
-
 /* Progress,Resize */
 .wp_themeSkin .mceBlocker {
 	position: absolute;
@@ -583,7 +581,6 @@
 	border: 1px dotted gray;
 }
 
-
 /* Formats */
 .wp_themeSkin .mce_p span.mceText {}
 .wp_themeSkin .mce_address span.mceText {
@@ -624,7 +621,6 @@
 	font-size: 12px;
 }
 
-
 /* Theme */
 .wp_themeSkin span.mce_undo {background-position:-500px -20px}
 .wp_themeSkin .mceButtonEnabled:hover span.mce_undo,
@@ -769,7 +765,6 @@
 .wp_themeSkin .mce_backcolor span.mceAction {background-position:-760px 0}
 .wp_themeSkin .mce_backcolorpicker {background-position:-760px 0}
 
-
 /* Plugins */
 .wp_themeSkin span.mce_advhr {background-position:-0px -20px}
 .wp_themeSkin span.mce_ltr {background-position:-20px -20px}
@@ -818,7 +813,6 @@
 .wp_themeSkin span.mce_ins {background-position:-960px -20px}
 .wp_themeSkin span.mce_pagebreak {background-position:0 -40px}
 
-
 /* border */
 .wp_themeSkin .mceExternalToolbar,
 .wp_themeSkin .mceButton,
@@ -939,7 +933,6 @@
 	border-color: #909090;
 }
 
-
 .wp_themeSkin table.mceSplitButton td {
 	background-color: #eee; /* Fallback */
 	background-image: -ms-linear-gradient(bottom, #ddd, #fff); /* IE10 */
@@ -1166,7 +1159,6 @@ html[dir="rtl"] .wp-switch-editor {
 	background-color: #ccc;
 }
 
-
 /*------------------------------------------------------------------------------
  wp-link
 ------------------------------------------------------------------------------*/
@@ -1361,7 +1353,6 @@ html[dir="rtl"] .wp-switch-editor {
 	float: right;
 }
 
-
 /*
  * Based on:
  * jQuery UI CSS Framework @VERSION
@@ -1386,19 +1377,16 @@ html[dir="rtl"] .wp-switch-editor {
 /* end clearfix */
 .ui-helper-zfix { width: 100%; height: 100%; top: 0; left: 0; position: absolute; opacity: 0; filter:Alpha(Opacity=0); }
 
-
 /* Interaction Cues
 ----------------------------------*/
 .ui-state-disabled { cursor: default !important; }
 
-
 /* Icons
 ----------------------------------*/
 
 /* states and images */
 .ui-icon { display: block; text-indent: -99999px; overflow: hidden; background-repeat: no-repeat; }
 
-
 /* Misc visuals
 ----------------------------------*/