webrtc-internals: remove explicit width from stats table

Removes the explicit width from the stats table which may cause issues unfold the last details element due to a scrollbar that happens because of very long DTLS fingerprints. May cause the stats table container to be positioned differently depending on the window width

Test Plan:
manually tick the box left of width on the .stats-table-container to get a visual preview, check this removes the bottom scrollbar

BUG=966330

Change-Id: I792b99d9cba80baa1c5dc90dd039dd9be831f76c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1626854Reviewed-by: Henrik Boström <hbos@chromium.org>
Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Cr-Commit-Position: refs/heads/master@{#662607}

content/browser/resources/media/webrtc_internals.css

@@ -48,7 +48,6 @@
 .stats-table-container {
   float: left;
   padding: 0 0 0 0;
-  width: 50em;
   overflow: auto;
 }