Disallow invalid inline style comments in stylesheets (#9099)

res/css/views/beta/_BetaCard.pcss

@@ -58,10 +58,10 @@ limitations under the License.
                     padding: 7px 40px;
                     width: auto;
                     flex: 1;
-                    white-space: nowrap; // text might overflow
+                    white-space: nowrap; /* text might overflow */
 
                     &:nth-child(1) {
-                        order: 2; // Place feedback button top and right
+                        order: 2; /* Place feedback button top and right */
                     }
                 }
             }
@@ -127,7 +127,7 @@ limitations under the License.
     color: $button-primary-fg-color;
     display: inline-block;
     vertical-align: text-bottom;
-    word-break: keep-all; // avoid multiple lines on CJK language
+    word-break: keep-all; /* avoid multiple lines on CJK language */
 
     &.mx_AccessibleButton {
         cursor: pointer;