- GUI designer - not really, but you're likely to be using a framework-specific GUI builder anyway. Then again, if you really wanted it, you could probably twist the artist-mode hard enough to draw mockups in it and save them as XML descriptions.
- Semantic refactoring - CEDET.
- Graphic visualization of CSS modes - Rainbow Mode, or just open a frikkin' browser.
- Integration of JavaScript frameworks with code-completion support and two way editing between CSS, HTML and JavaScript code - not sure what you mean by "two-way editing" here, but you have code completion, CSS/HTML/JS support, and - as I mentioned - a way to push all of this back and forth between Emacs and a browser.
- Graphical visualization of data structures in debugger - depending on how complex you want to be, but for most practical uses the answer is "yes, Emacs handles it"
- Graphical support of heap data and threads in debugger - again, if by "graphical support" you mean trees, not bubble-graphs and pretty pictures, then yes
- ... - type it up, M-x eval buffer, and carry on.