Not trivially. The easiest way would be to write the current file to the temp dir, then launch that file.. but, this would break any relative links (images, scripts, CSS files)
Add a bundle:
Input: Entire Document
Output: Discard
Scope Selector: source.html
And the script:
#!/usr/bin/env python2.5
import os
import sys
import random
import tempfile
import subprocess
fname = os.environ.get("TM_FILEPATH", "Untitled %s.html" % random.randint(100, 1000))
fcontent = sys.stdin.read()
fd, name = tempfile.mkstemp()
print name
open(name, "w+").write(fcontent)
print subprocess.Popen(["open", "-a", "Firefox", name]).communicate()
As I said, that wont work with relative resource links, which is probably a big problem.. Another option is to modify the following line of code, from the exiting "Refresh Browsers" command:
osascript <<'APPLESCRIPT'
tell app "Firefox" to Get URL "JavaScript:window.location.reload();" inside window 1
APPLESCRIPT
Instead of having the javascript reload the page, it could clear it, and write the current document using a series of document.write() calls. The problem with this is you can't guarantee the current document is the one you want to replace.. Windows 1 could have changed to another site etc, especially with tabbed browsing..
Finally, an option that doesn't have a huge drawback: Use version control, particularly one of the "distributed" ones, where you don't have to send your changes to a remote server - git, mercurial, darcs, bazaar etc (all have TextMate integration also)
If your code is in version control, it doesn't matter if you save before previewing, you can also always go back to your last-commited version if you break something and lose the undo buffer.