Don't allow scripts to run when a node is being adopted.

      Running a script in the middle of rescoping nodes can break a lot of invariants and leave DOM in an inconsistent state.

This patch adds a ScriptForbiddenScope in TreeScope::adoptIfNeeded to ensure it never happens.

BUG=605766

Review URL: https://codereview.chromium.org/1910403003

Cr-Commit-Position: refs/heads/master@{#389425}