Web SQL: Remove more worker-related code.

- Drop worker support from DatabaseClient.
- Remove WorkerGlobalScope support of DatabaseContext::allowDatabaseAccess.

BUG=397429
TEST=none; No behavior changes.

Review URL: https://codereview.chromium.org/564713002

git-svn-id: svn://svn.chromium.org/blink/trunk@181857 bbb929c8-8fbe-4397-9dbb-9b2b20218538
remove broken import

R=ojan@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/567673003

git-svn-id: svn://svn.chromium.org/blink/trunk@181858 bbb929c8-8fbe-4397-9dbb-9b2b20218538