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

Committed: https://crrev.com/4347d56a6919ae06a70e4a4a8b2f1179cf47bc7e
Cr-Commit-Position: refs/heads/master@{#28767}

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

Cr-Commit-Position: refs/heads/master@{#28771}