Make the cursor show up consistently in the white theme, credits to bmc for finding the issue

plugins/supported/whitetheme/index.js

@@ -198,7 +198,6 @@ exports.whiteTheme = function() {
             },
 
             highlighterBG: {
-                plain:      '#ffffff',
                 addition:   '#008000',
                 deletion:   '#800000'
             },