misc strictMath compliance fixes

less/dropdowns.less

@@ -142,7 +142,7 @@
   right: 0;
   bottom: 0;
   top: 0;
-  z-index: @zindex-dropdown - 10;
+  z-index: (@zindex-dropdown - 10);
 }
 
 // Right aligned dropdowns

less/forms.less

@@ -352,7 +352,7 @@ input[type="checkbox"],
   // and other content below items
   .radio,
   .checkbox {
-    min-height: @line-height-computed + (@padding-base-vertical + 1);
+    min-height: (@line-height-computed + (@padding-base-vertical + 1));
   }
 
   // Make form groups behave like rows

less/panels.less

@@ -102,7 +102,7 @@
 .panel-heading {
   padding: 10px 15px;
   border-bottom: 1px solid transparent;
-  .border-top-radius(@panel-border-radius - 1);
+  .border-top-radius((@panel-border-radius - 1));
 
   > .dropdown .dropdown-toggle {
     color: inherit;
@@ -126,7 +126,7 @@
   padding: 10px 15px;
   background-color: @panel-footer-bg;
   border-top: 1px solid @panel-inner-border;
-  .border-bottom-radius(@panel-border-radius - 1);
+  .border-bottom-radius((@panel-border-radius - 1));
 }