ARM: Make DoStoreKeyedFixedDoubleArray faster; don't allow conditional Vmov

ARM: Make DoStoreKeyedFixedDoubleArray faster; don't allow conditional Vmov

This patch makes us generate faster code for DoStoreKeyedFixedDoubleArray,
by using a branch rather than a conditional Vmov instruction.

Conditional VFP instructions are not a great idea in general, and it was
especially bad in this case because Vmov expands to a bunch of instructions.
For this reason, the patch also removes the 'cond' parameter from Vmov.

Thanks to Rodolph for pointing me to this!

BUG=none

Review URL: https://chromiumcodereview.appspot.com/12316096
Patch from Hans Wennborg <hans@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@13722 ce2b1a6d-e550-0410-aec6-3dcde31c8c00