Add back the inspector_strings target

It's only built if use_third_part_translations=1.

Also pull in the translations from launchpad.net.

Review URL: http://codereview.chromium.org/6334090

git-svn-id: http://src.chromium.org/svn/trunk/src/build@73816 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -180,6 +180,7 @@
     'library%': '<(library)',
     'component%': '<(component)',
     'use_titlecase_in_grd_files%': '<(use_titlecase_in_grd_files)',
+    'use_third_party_translations%': '<(use_third_party_translations)',
     'remoting%': '<(remoting)',
 
     # The release channel that this build targets. This is used to restrict