- Adds vabs, vneg, vmul, vext, vzip, vrev instructions.
- Adds Swizzle function to macro assembler.
- Simplifies if-else logic in disassembler, simulator, for Neon special.
- Some refactoring of Neon assembler, macro-assembler tests.

LOG=N
BUG=v8:4124

Review-Url: https://codereview.chromium.org/2579913002
Cr-Commit-Position: refs/heads/master@{#41781}