ExpandableList: Allow `overflow: hidden` for long content

This allows the rows of and expandable list to not overflow and show
an ellipsis (...) instead.

This will be used in https://crrev.com/c/3474160.

Bug: 1288158
Change-Id: I53fe095f6a5d808073c7949769d70467601ad66c
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3500428
Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Commit-Queue: Wolfgang Beyer <wolfi@chromium.org>
diff --git a/front_end/ui/components/expandable_list/expandableList.css b/front_end/ui/components/expandable_list/expandableList.css
index 47b3c10..9599408 100644
--- a/front_end/ui/components/expandable_list/expandableList.css
+++ b/front_end/ui/components/expandable_list/expandableList.css
@@ -4,6 +4,10 @@
  * found in the LICENSE file.
  */
 
+:host {
+  overflow: hidden;
+}
+
 div {
   line-height: 1.7em;
 }
@@ -53,3 +57,9 @@
   font-family: inherit;
   font-size: inherit;
 }
+
+.text-ellipsis {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}