- Adds move/swap handling for 4 and 16 bytes to ia32.
- Register allocator now only requests 4 bytes for floats on ia32 and arm.
- We probably need similar support in mips.

LOG=N
BUG=v8:4124

Review-Url: https://codereview.chromium.org/2027043002
Cr-Commit-Position: refs/heads/master@{#37714}