When calculating Math.pow where the exponent is a smi use a simple loop to calculate the result.

Added support for the vmov instruction moving from one doubleword extension register to another.

Added some Math.pow tests which partially covers what is in the Sputnik tests.
Review URL: http://codereview.chromium.org/2804033

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4990 ce2b1a6d-e550-0410-aec6-3dcde31c8c00