Bug 1544483 - Add missing `.../context.js` file to .../browser.ini r=loganfsmyth

Differential Revision: https://phabricator.services.mozilla.com/D27533

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

devtools/client/inspector/rules/test/browser.ini

@@ -41,6 +41,7 @@ support-files =
   doc_variables_2.html
   doc_variables_3.html
   head.js
+  !/devtools/client/debugger/test/mochitest/helpers/context.js
   !/devtools/client/inspector/test/head.js
   !/devtools/client/inspector/test/shared-head.js
   !/devtools/client/shared/test/shared-head.js