Adds SIMD 128 alignment sizes and masks.
Adds support in Heap for SIMD alignments and fills.
Reworks cctest so that each test independently aligns its allocation address, rather than depending on the previous tests ending state. Adds test cases for SIMD.

LOG=N
BUG=v8:4124

Review URL: https://codereview.chromium.org/1159453004

Cr-Commit-Position: refs/heads/master@{#28767}