Web Inspector: Web Inspector: Specify return type of WebInspector.UIString
https://bugs.webkit.org/show_bug.cgi?id=110095

Reviewed by Pavel Feldman.

Specify return type of WebInspector.UIString.
Fix new js-compiler warnings.

This change will increase type coverage by 0.4% (to 81%)

* inspector/front-end/ObjectPropertiesSection.js: Fix type errors.
* inspector/front-end/UIString.js:
(WebInspector.UIString): Return type specified.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144061 268f45cc-cd09-0410-ab3c-d52691b4dbfc