Fix .leaflet-bar style for a single button bar

Should have the same border radius on all corners.

dist/leaflet.css

@@ -217,12 +217,16 @@
 	background-color: #f4f4f4;
 	}
 .leaflet-bar a:first-child {
-	-webkit-border-radius: 4px 4px 0 0;
-	        border-radius: 4px 4px 0 0;
+	-webkit-border-top-left-radius: 4px;
+	        border-top-left-radius: 4px;
+	-webkit-border-top-right-radius: 4px;
+	        border-top-right-radius: 4px;
 	}
 .leaflet-bar a:last-child {
-	-webkit-border-radius: 0 0 4px 4px;
-	        border-radius: 0 0 4px 4px;
+	-webkit-border-bottom-left-radius: 4px;
+	        border-bottom-left-radius: 4px;
+	-webkit-border-bottom-right-radius: 4px;
+	        border-bottom-right-radius: 4px;
 	border-bottom: none;
 	}
 .leaflet-bar a.leaflet-disabled {
@@ -240,12 +244,16 @@
 	height: 30px;
 	}
 .leaflet-touch .leaflet-bar a:first-child {
-	-webkit-border-radius: 7px 7px 0 0;
-	        border-radius: 7px 7px 0 0;
+	-webkit-border-top-left-radius: 7px;
+	        border-top-left-radius: 7px;
+	-webkit-border-top-right-radius: 7px;
+	        border-top-right-radius: 7px;
 	}
 .leaflet-touch .leaflet-bar a:last-child {
-	-webkit-border-radius: 0 0 7px 7px;
-	        border-radius: 0 0 7px 7px;
+	-webkit-border-bottom-left-radius: 7px;
+	        border-bottom-left-radius: 7px;
+	-webkit-border-bottom-right-radius: 7px;
+	        border-bottom-right-radius: 7px;
 	border-bottom: none;
 	}