fix(css): Fix missing calc() statements (#4156)

Closes #4155

ui/less/ad_controls.less

@@ -82,7 +82,7 @@
    * That divided by 2 is margin on one side, so we take that, and move the
    * button from its normal position to the right by that percentage.
    */
-  right: (100 - @bottom-controls-width) / 2 * -1;
+  right: calc((100 - @bottom-controls-width) / 2 * -1);
   display: flex;
   flex-direction: row;
   margin: 0;

ui/less/buttons.less

@@ -26,7 +26,7 @@
    *
    * Based on tips from https://stackoverflow.com/a/12925343 */
   box-sizing: border-box;
-  padding: @play-button-size-percentage / 2;
+  padding: calc(@play-button-size-percentage / 2);
   width: 0;
   height: 0;
 

ui/less/containers.less

@@ -337,20 +337,20 @@
 
 .shaka-spinner {
   /* This uses the same trickery as the big play button define
-  the spinner's width and height. See .shaka-play-button
-  for the detailed explanation. */
+   * the spinner's width and height. See .shaka-play-button
+   * for the detailed explanation. */
 
   /* For the padding thing to work, spinner div needs to be an
   overlay-parent and spinner svg - an overlay child. */
   .overlay-parent();
 
   margin: 0;
   box-sizing: border-box;
-  padding: @spinner-size-percentage / 2;
+  padding: calc(@spinner-size-percentage / 2);
   width: 0;
   height: 0;
 
   /* Add a bit of a white shadow to keep our black spinner visible
-  on a black background. */
+   * on a black background. */
   filter: drop-shadow(0 0 2px rgba(255 255 255 / 50%));
 }

ui/less/range_elements.less

@@ -39,7 +39,7 @@
   .overlay-parent();
 
   /* Vertical margins to occupy the same space as the thumb. */
-  margin: (@thumb-size - @track-height)/2 6px;
+  margin: calc((@thumb-size - @track-height) / 2) 6px;
 
   /* Smaller height to contain the background for the virtual track. */
   height: @track-height;
@@ -109,7 +109,7 @@
 
   /* Position the top of the range element so that it is centered on the
    * container. Note that the container is actually smaller than the thumb. */
-  top: (@track-height - @thumb-size) / 2;
+  top: calc((@track-height - @thumb-size) / 2);
 
   /* Make sure clicking at the very top of the bar still takes effect and is not
    * confused with clicking the video to play/pause it. */

ui/less/tooltip.less

@@ -48,7 +48,7 @@
 
       /* Override .material-icons-round text styling */
       font-family: Roboto-Regular, Roboto, sans-serif;
-      line-height: @material-icons-width / 2;
+      line-height: calc(@material-icons-width / 2);
       white-space: nowrap;
       font-size: 13px;
 
@@ -60,10 +60,10 @@
 
       /* Positioning */
       position: absolute;
-      bottom: @material-icons-width + 5px;
+      bottom: calc(@material-icons-width + 5px);
 
       /* Left attribute is set to half of the width of the parent button */
-      left: @material-icons-width / 2;
+      left: calc(@material-icons-width / 2);
 
       /* The tooltip is also translated 50% to appear centered */
       .translateX(-0.5);