Remove StringBuilder::appendLiteral.

We can just rely on the append(StringView) version instead. This does
mean we have to take 2 branches in some cases, but it should be
very minimal and since the code is inline the compiler can also
likely eliminate it.

BUG=615174

Review-Url: https://codereview.chromium.org/2017053003
Cr-Commit-Position: refs/heads/master@{#396601}
87 files changed