Fix typo which prevented increaseFontSize() and decreaseFontSize() from working in Chrome and Safari.

Fix typo which prevented increaseFontSize() and decreaseFontSize() from working in Chrome and Safari.

This typo was introduced in https://github.com/jwysiwyg/jwysiwyg/commit/5773caf89924f2816e0c13ff8f14bab5856241d4

$.browser.safari was changed to $.browser.opera. However, opera is handled in the previous block, so this webkit-specific code never got run. Instead, Chrome and Safari would both run the final else block (console.error("Internet Explorer?");)