This patch prevents taking the low/high part of a double-precision VFP register that has no corresponding single-precision VFP registers.

BUG=none
TEST=Added to test-disasm-arm.cc, test-assembler-arm.cc

Review URL: https://codereview.chromium.org/19560003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15885 ce2b1a6d-e550-0410-aec6-3dcde31c8c00