Many companies and organizations combine two words, and capitalize them both, forming their name (ex: SuperUser and StackExchange). Both words individually are spelled correctly, however because there is no space, the browser gets confused, and underlines them, letting us know they think they are misspelled.
How can I get Google's Chrome or Mozilla's Firefox or even Microsoft's Internet Explorer and Microsoft office to recognize the capital letter in the middle of a word as beginning a new word, and therefore not marking the word as misspelled (unless the 2nd word is misspelled, ex: SuperUsr)