[M138] Set flex none for the binary toolbar in the network panel

After the UI engineering migration, the toolbar doesn't show properly
if the main content is large. Since we wrapped the toolbar
in a a WidgetElement, the widget styles applied (flex: auto).

To fix this, we need to override the flex properties.

Before: https://i.imgur.com/SAQHvg3.png
After: https://i.imgur.com/pgcTAAo.png
Bug: 433417235
Fixed: 434252774
Change-Id: Ie465f8b24ed3e0b5c194055c88faa510299fd58d
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6779623
Auto-Submit: Kim-Anh Tran <kimanh@chromium.org>
Reviewed-by: Kateryna Prokopenko <kprokopenko@chromium.org>
Commit-Queue: Kim-Anh Tran <kimanh@chromium.org>
(cherry picked from commit e53600c565c9ca6376c178bdfecf3126e0283abc)
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6793466
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
diff --git a/front_end/panels/network/binaryResourceView.css b/front_end/panels/network/binaryResourceView.css
index f0731f6..46c23ba 100644
--- a/front_end/panels/network/binaryResourceView.css
+++ b/front_end/panels/network/binaryResourceView.css
@@ -8,6 +8,7 @@
   border-top: 1px solid var(--sys-color-divider);
   border-bottom: 0;
   padding-left: 5px;
+  flex: none;
 }
 
 .binary-view-copied-text {