MD History: fix side nav layout in RTL

chrome/browser/resources/md_history/app.vulcanized.html

Index: chrome/browser/resources/md_history/app.vulcanized.html
diff --git a/chrome/browser/resources/md_history/app.vulcanized.html b/chrome/browser/resources/md_history/app.vulcanized.html
index 425ccb7dbf9be2a2959e50125a8c28d1734f72ac..09265a6a1a2c7fe47fc5798fb511c8a8b08a3f50 100644
--- a/chrome/browser/resources/md_history/app.vulcanized.html
+++ b/chrome/browser/resources/md_history/app.vulcanized.html
@@ -3963,7 +3963,7 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
       }
 
       /* Sizing this with flex causes slow load performance, see
-         crbug.com/618153. */
+       * crbug.com/618153. TODO(dbeam): is this still an issue? */
       #main-container {
         height: calc(100% - var(--toolbar-height));
       }
@@ -3976,6 +3976,10 @@ subject to an additional IP rights grant found at http://polymer.github.io/PATEN
         float: left;
       }
 
+      :host-context([dir='rtl']) #content-side-bar {
+        float: right;
+      }
+
       #content,
       #content > * {
         height: 100%;