Media Controls: Fix overflow icon padding

Fix overflow icon padding on the new media controls if the overflow
icons are enabled.

BUG=787445

Change-Id: I2f2ec5a56839ccada45feebcd10b18fcbb82a749
Reviewed-on: https://chromium-review.googlesource.com/813915Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522409}

third_party/WebKit/Source/modules/media_controls/resources/modernMediaControls.css

@@ -394,8 +394,8 @@ video::-internal-media-controls-overflow-menu-list-item {
 }
 
 label[pseudo="-internal-media-controls-overflow-menu-list-item"] input {
-  margin-left: -22px;
-  margin-right: 2px;
+  margin-left: -9px;
+  margin-right: 6px;
 }
 
 audio::-internal-media-controls-text-track-list-header:hover,