Don't pass the "at start" parameter to native RegExp

Don't pass the "at start" parameter to native RegExp

As the start index is already passed it is easy to calculate the "at start" boolean in generated code. Also as direct entry has been implemented this needs to be done in generated code anyway, and therefore might as well be moved to the generated code for RegExp. The "at start" value is now calcualted as a local variable on the native RegExp frame based on the value of the start index argument.

The x64 version have been tested on both Linux and 64-bit Windows Vista.

For ARM I have tested cctest/test-regexp on ARM hardware, but the rest of the tests have only been run on the ARM simulator.
Review URL: http://codereview.chromium.org/554078

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3709 ce2b1a6d-e550-0410-aec6-3dcde31c8c00