make DateParser::TimeComposer handle 1-2 digits millisecond values

make DateParser::TimeComposer handle 1-2 digits millisecond values

see http://code.google.com/p/v8/issues/detail?id=944
This patch makes DateParser::TimeComposer process times that have
millisecond values with only 1 or 2 digits.

Without this patch, Date.parse("2010-11-25T22:02:30.5") returns
1290690150005 and
Date.parse("2010-11-25T22:02:30.5") == Date.parse("2010-11-25T22:02:30.005")
evaluates to true.

With this patch, Date.parse("2010-11-25T22:02:30.5") returns
1290690150500 instead, and
Date.parse("2010-11-25T22:02:30.5") == Date.parse("2010-11-25T22:02:30.005")
evaluates to false.

Review URL: http://codereview.chromium.org/5336005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5893 ce2b1a6d-e550-0410-aec6-3dcde31c8c00