Fix some typos in the English locale (fixes #4663) (#4793)

webapp/root.jsx

@@ -41,7 +41,7 @@ function preRenderSetup(callwhendone) {
         });
 
         if (window.mm_config && window.mm_config.EnableDeveloper === 'true') {
-            window.ErrorStore.storeLastError({type: 'developer', message: 'DEVELOPER MODE: A javascript error has occured.  Please use the javascript console to capture and report the error (row: ' + line + ' col: ' + column + ').'});
+            window.ErrorStore.storeLastError({type: 'developer', message: 'DEVELOPER MODE: A JavaScript error has occurred.  Please use the JavaScript console to capture and report the error (row: ' + line + ' col: ' + column + ').'});
             window.ErrorStore.emitChange();
         }
     };