Core: Resolve csslint issues with the IE filter property

IE filter property violates standard CSS parsing rules. Because of that, IE 8
added `-ms-filter` which accepts the same values but quoted:
https://web.archive.org/web/20101112132308/http://blogs.msdn.com/b/ie/archive/2008/09/08/microsoft-css-vendor-extensions.aspx
Both `filter` & `-ms-filter` serialize to the same `filter` property in
`currentStyle`.

This commit switches to that new property to resolve csslint issues.

Closes gh-1939

themes/base/core.css

@@ -50,7 +50,7 @@
 	left: 0;
 	position: absolute;
 	opacity: 0;
-	filter:Alpha(Opacity=0); /* support: IE8 */
+	-ms-filter: "alpha(opacity=0)"; /* support: IE8 */
 }
 
 .ui-front {

themes/base/progressbar.css

@@ -20,7 +20,7 @@
 .ui-progressbar .ui-progressbar-overlay {
 	background: url("data:image/gif;base64,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");
 	height: 100%;
-	filter: alpha(opacity=25); /* support: IE8 */
+	-ms-filter: "alpha(opacity=25)"; /* support: IE8 */
 	opacity: 0.25;
 }
 .ui-progressbar-indeterminate .ui-progressbar-value {

themes/base/theme.css

@@ -167,18 +167,18 @@ a.ui-button:active,
 .ui-widget-content .ui-priority-secondary,
 .ui-widget-header .ui-priority-secondary {
 	opacity: .7;
-	filter:Alpha(Opacity=70); /* support: IE8 */
+	-ms-filter: "alpha(opacity=70)"; /* support: IE8 */
 	font-weight: normal;
 }
 .ui-state-disabled,
 .ui-widget-content .ui-state-disabled,
 .ui-widget-header .ui-state-disabled {
 	opacity: .35;
-	filter:Alpha(Opacity=35); /* support: IE8 */
+	-ms-filter: "alpha(opacity=35)"; /* support: IE8 */
 	background-image: none;
 }
 .ui-state-disabled .ui-icon {
-	filter:Alpha(Opacity=35); /* support: IE8 - See #6059 */
+	-ms-filter: "alpha(opacity=35)"; /* support: IE8 - See #6059 */
 }
 
 /* Icons
@@ -431,7 +431,7 @@ html .ui-icon-blank { background-image: none; }
 .ui-widget-overlay {
 	background: #aaaaaa/*{bgColorOverlay}*/ /*{bgImgUrlOverlay}*/ /*{bgOverlayXPos}*/ /*{bgOverlayYPos}*/ /*{bgOverlayRepeat}*/;
 	opacity: .3/*{opacityOverlay}*/;
-	filter: Alpha(Opacity=30)/*{opacityFilterOverlay}*/; /* support: IE8 */
+	-ms-filter: "alpha(opacity=30)"/*{opacityFilterOverlay}*/; /* support: IE8 */
 }
 .ui-widget-shadow {
 	-webkit-box-shadow: 0/*{offsetLeftShadow}*/ 0/*{offsetTopShadow}*/ 5px/*{thicknessShadow}*/ #666666/*{bgColorShadow}*/;