DevTools: Fix text going out when adding a new Watch Expression.

BUG=338654
R=apavlov
NOTRY=true

Review URL: https://codereview.chromium.org/178543014

git-svn-id: svn://svn.chromium.org/blink/trunk@168381 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/devtools/front_end/inspector.css

@@ -1728,6 +1728,7 @@ li.editing-sub-part .delete-button {
 .watch-expressions > li.editing-sub-part .text-prompt {
     display: block;
     width: 100%;
+    overflow: hidden;
 }
 
 .watch-expressions > li.editing-sub-part .value,