Merge pull request #997 from matrix-org/t3chguy/external_electron

maybe fixxy [Electron] external thing?

karma.conf.js

@@ -177,6 +177,11 @@ module.exports = function (config) {
                 ],
             },
             devtool: 'inline-source-map',
+            externals: {
+                // Don't try to bundle electron: leave it as a commonjs dependency
+                // (the 'commonjs' here means it will output a 'require')
+                "electron": "commonjs electron",
+            },
         },
 
         webpackMiddleware: {