Simplify template literal raw string creation

BUG=v8:3710
LOG=Y
R=dslomov@chromium.org, marja@chromium.org

Review URL: https://codereview.chromium.org/768203002

Cr-Commit-Position: refs/heads/master@{#25640}
MIPS64: [turbofan] Add checked load/store operators.

Port c516d4f09408879602520748333754d3866224fb

BUG=

Review URL: https://codereview.chromium.org/773113005

Cr-Commit-Position: refs/heads/master@{#25641}