Bug 1599805 - Fix React props in JSTerm. r=Honza.

Differential Revision: https://phabricator.services.mozilla.com/D55240

--HG--
extra : moz-landing-system : lando

devtools/client/webconsole/components/Input/JSTerm.js

@@ -1230,7 +1230,7 @@ class JSTerm extends Component {
         className: "jsterm-input-container devtools-input devtools-monospace",
         key: "jsterm-container",
         "aria-live": "off",
-        tabindex: -1,
+        tabIndex: -1,
         onContextMenu: this.onContextMenu,
         ref: node => {
           this.node = node;