Change locationFromPosition() and locationFromLine() to use a binary search to locate line numbers from position numbers.  Modify test debug-sourceinfo.js to include more tests, including error conditions.

Patch by Matt Hanselman, see http://codereview.chromium.org/118371.

BUG=213
TEST=test/mjsunit/debug-sourceinfo.js
Review URL: http://codereview.chromium.org/118425

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2125 ce2b1a6d-e550-0410-aec6-3dcde31c8c00