Remove IE 6 specific code

Removing further CSS for Internet Explorer 6.
Follow-up to I0f98c61cf9108c0a91769e9b7044023b01f974ed.

Change-Id: I85a7570c97f9b618a7946dc20367b54e72d31b3e

components/common.less

@@ -2,12 +2,6 @@
  * Any rules which should not be flipped automatically in right-to-left situations should be
  * prepended with @noflip in a comment block.
  *
- * This stylesheet employs a few CSS trick to accomplish compatibility with a wide range of web
- * browsers. The most common trick is to use some styles in IE6 only. This is accomplished by using
- * a rule that makes things work in IE6, and then following it with a rule that begins with
- * "html > body" or use a child selector ">", which is ignored by IE6 because it does not support
- * the child selector. You can spot this by looking for the "OVERRIDDEN BY COMPLIANT BROWSERS" and
- * "IGNORED BY IE6" comments.
  */
 @import 'mediawiki.mixins';
 
@@ -84,6 +78,7 @@ body {
 	.mw-indicator {
 		display: inline-block;
 		zoom: 1;
+		// Support: IE7
 		*display: inline; // stylelint-disable declaration-block-no-duplicate-properties
 	}
 }

components/search.less

@@ -92,8 +92,6 @@
 		cursor: pointer;
 		/* Hide button text and replace it with the image. */
 		text-indent: -99999px;
-		/* Needed to make IE6 respect the text-indent. */
-		line-height: 1;
 		/* Opera 12 on RTL flips the text in a funny way without this. */
 		/* @noflip */
 		direction: ltr;

components/watchstar.less

@@ -12,8 +12,6 @@
 		width: 28px;
 		/* This hides the text but shows the background image */
 		padding-top: 3.1em;
-		/* Only applied in IE6 */
-		_margin-top: -0.8em;
 		height: 0;
 		overflow: hidden;
 		background-position: 5px 60%;

skinStyles/mediawiki.special.preferences.styles.less

@@ -31,7 +31,6 @@
 		background-position: bottom right;
 		background-repeat: no-repeat;
 
-		/* Sadly, IE6 won't understand this */
 		&:first-child {
 			margin-left: 1px;
 		}